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  • 51.
    Chen, Zhuo Yuan
    et al.
    wedish Corrosion Institute, Sweden.
    Zakipur, S.
    Persson, D.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Corrosion Science (closed 20081231).
    The Combined Effects of Gaseous pollutants and Sodium Chloride Particles on the Atmospheric Corrosion of Pure Copper2005In: Corrosion, ISSN 0010-9312, E-ISSN 1938-159X, Vol. 61, no 11, p. 1022-1034Article in journal (Refereed)
    Abstract [en]

    The atmospheric corrosion of pure copper has been investigated after the deposition of sodium chloride (NaCI) particles and exposure to humid air containing gaseous pollutants. Microgravimetry, Fourier transform infrared (FTIR) micro-spectroscopy, and scanning electron microscopy with x-ray microanalysis were used for the investigation of corrosion processes and products. The effect of NaCl particles on the mass gain was much higher than that of gaseous pollutants. With deposition of NaCl particles on the copper surfaces, the corrosion rate increased significantly, with severe corrosion attack mainly localized to the NaCl particle clusters. A similar corrosion rate was found, however, after exposure to pure humid air and to humid air containing gaseous pollutants, sulfur dioxide (SO2), ozone (O-3), nitrogen dioxide (NO2), and SO2 + NO2. The corrosion rate was not dependent on the concentration of the pollutants. However, this was not the case for the combination of SO2 and O-3, leading to a significantly higher corrosion rate at higher concentrations. Exposure of copper samples with NaCl particles deposited resulted in unevenly distributed corrosion product clusters, with a distribution of corrosion products that could be associated with the locations of the particle clusters. Around the particle clusters, the corrosion resulted in areas with different amounts of corrosion products. After 10 days of exposure to humid air containing 100 ppb SO2 and 100 ppb NO2 + SO2, cuprite (Cu2O), paratacamite (Cu-2[OH](3)Cl), carbonate (CO32-), and sulfate (SO42-) were observed mainly in the area of the original particle cluster, with some sutfate and copper hydroxysulfate also in the areas outside. After 10 days of exposure to humid air containing 100 ppb O-3 + SO2, cuprite (Cu2O), hydroxychloride (maybe paratacamite, Cu-2[OH](3)Cl), carbonate (CO32-), and sutfate (SO42-) were observed in the area of the original particle cluster. A circular zone containing brochantite (Cu-4[OH](6)SO4) was formed around and outside of the original particle cluster, and the formation of this phase was promoted by the presence of NaCl particles on the surface. The location of anodic and cathodic reactions during the corrosion process leads to the distribution of different corrosion products on the surface.

  • 52.
    Cheng, Ming
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Aitola, Kerttu
    Chen, Cheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Zhang, Fuguo
    Liu, Peng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Sveinbjornsson, Kari
    Hua, Yong
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Boschloo, Gerrit
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Dalian Univ Technol.
    Acceptor Donor Acceptor type ionic molecule materials for efficient perovskite solar cells and organic solar cells2016In: NANO ENERGY, ISSN 2211-2855, Vol. 30, p. 387-397Article in journal (Refereed)
    Abstract [en]

    Perovskite solar cells (PSCs) have attracted significant interest and hole transporting materials (HTMs) play important roles in achieving high efficiency. Here, we report additive free ionic type HTMs that are based on 2-ethylhexyloxy substituted benzodithiophene (BDT) core unit. With the ionization of end-capping pyridine units, the hole mobility and conductivity of molecular materials are greatly improved. Applied in PSCs, ionic molecular material M7-TFSI exhibits the highest efficiency of 17.4% in the absence of additives [lithium bis(trifluor-omethanesulfonyl)imide and 4-tert-butylpyridine]. The high efficiency is attributed to a deep highest occupied molecular orbital (HOMO) energy level, high hole mobility and high conductivity of M7-TFSI. Moreover, due to the higher hydrophobicity of M7-TFSI, the corresponding PSCs showed better stability than that of Spiro-OMeTAD based ones. In addition, the strong absorption and suitable energy levels of materials (M6, M7-13r and M7-TFSI) also qualify them as donor materials in organic solar cells (OSCs) and the devices containing M7-TFSI as donor material displayed an efficiency of 6.9%.

  • 53.
    Chiu, Justin NingWei
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Martin, Viktoria
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Setterwall, Fredrik
    A Review of Thermal Energy Storage Systems with Salt Hydrate Phase Change Materials for Comfort Cooling2009In: 11th International Conference on Thermal Energy Storage, June 14-17 , 2009, Stockholm, Sweden., 2009Conference paper (Refereed)
    Abstract [en]

    This paper presents a review of cold thermal energy storage technologies. Latent heat thermal energy storage (LHTES) with phase change materials (PCMs) deserves attention as they provide high energy density and small temperature change interval upon melting/solidifying. Salt hydrates are especially interesting since they demonstrate high latent heat of fusion, high thermal conductivity, low flammability, and facilitate the use in buildings as compared to organic PCMs. A review of system performance obtained from experimental work, theoretical analyses and real case studies has however shown some material shortcomings. To reach cost effectiveness, future work in the field of LHTES with salt hydrates lies in finding suitable methods for limiting incongruent melting and subcooling without compromising the storage density. Also, system integration of LHTES in cold applications can be further developed in terms of innovative design for high power and storage capacity, load optimized sizing, controls, and elimination of PCM encapsulation.

  • 54.
    Choi, Hyungryul J.
    et al.
    MIT, Dept Mech Engn, Cambridge, MA 02139 USA.;1 Infinite Loop, Cupertino, CA 95014 USA..
    Park, Kyoo-Chul
    MIT, Dept Mech Engn, Cambridge, MA 02139 USA.;Northwestern Univ, Dept Mech Engn, Evanston, IL 60208 USA..
    Lee, Hyomin
    MIT, Dept Chem Engn, Cambridge, MA 02139 USA.;Harvard Univ, John A Paulson Sch Engn & Appl Sci, Cambridge, MA 02138 USA..
    Crouzier, Thomas
    KTH, School of Biotechnology (BIO). MIT, Dept Biol Engn, 77 Massachusetts Ave, Cambridge, MA 02139 US.
    Rubner, Michael F.
    MIT, Dept Mat Sci & Engn, Cambridge, MA 02139 USA..
    Cohen, Robert E.
    MIT, Dept Chem Engn, Cambridge, MA 02139 USA..
    Barbastathis, George
    MIT, Dept Mech Engn, Cambridge, MA 02139 USA.;Singapore MIT Alliance Res & Technol SMART Ctr, Singapore, Singapore..
    McKinley, Gareth H.
    MIT, Dept Mech Engn, Cambridge, MA 02139 USA..
    Superoleophilic Titania Nanoparticle Coatings with Fast Fingerprint Decomposition and High Transparency2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 9, p. 8354-8360Article in journal (Refereed)
    Abstract [en]

    Low surface tension sebaceous liquids such as human fingerprint oils are readily deposited on high energy surfaces such as clean glass, leaving smudges that significantly lower transparency. There have been several attempts to prevent formation of these dactylograms on glass by employing oil-repellent textured surfaces. However, nanotextured superoleophobic coatings typically scatter visible light, and the intrinsic thermodynamic metastability of the composite superoleophobic state can result in failure of the oil repellency under moderate contact pressure. We develop titania-based porous nanoparticle coatings that are superoleophilic and highly transparent and which exhibit short time scales for decomposition of fingerprint oils under ultraviolet light. The mechanism by which a typical dactylogram is consumed combines wicking of the sebum into the nanoporous titania structure followed by photocatalytic degradation. We envision a wide range of applications because these TiO2 nanostructured surfaces remain photocatalytically active against fingerprint oils in natural sunlight and are also compatible with flexible glass substrates.

  • 55. Christensen, M
    et al.
    Iversen, BB
    Bertini, L
    Gatti, C
    Toprak, Muhammet S.
    KTH, Superseded Departments, Materials Science and Engineering.
    Muhammed, Mamoun
    KTH, Superseded Departments, Materials Science and Engineering.
    Nishibori, E
    Structural study of Fe doped and Ni substituted thermoelectric skutterudites by combined synchrotron and neutron powder diffraction and ab initio theory2004In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 96, no 6, p. 3148-3157Article in journal (Refereed)
    Abstract [en]

    We present neutron and synchrotron powder-diffraction investigations as well as ab initio calculations to elucidate delicate structural features in doped skutterudites. Samples with assumed Fe doping were investigated (FeyCo4Sb12, y=0.4, 0.8, 1.0, and 1.6), as well as samples with formal Ni substitution (Co4-xNixSb12, x=0, 0.4, 0.8, and 1.2). The present study serves as a case story for the determination of fine structural details of thermoelectric skutterudites by diffraction methods in combination with ab initio calculations. We illustrate the problem of fluorescence in the conventional x-ray powder diffraction on the Fe-doped samples by a comparison with the neutron powder-diffraction data. On the series of the Ni-substituted samples, the neutron powder-diffraction data were collected to investigate the exact sitting of the Ni. The sample with the highest Ni substitution (Co2.8Ni1.2Sb12) was also used for high resolution, high-energy synchrotron powder diffraction measurements. These revealed that the sample consists of two skutterudite phases. A complete description of the Ni-substituted samples was obtained in tandem with ab initio calculations, which show that the system contains a Ni-rich (Co0.38Ni3.62Sb12) and a Ni-poor (Co3.76Ni0.24Sb12)) skutterudite phases.

  • 56.
    Chulapakorn, T.
    et al.
    Uppsala Univ, Dept Phys & Astron, POB 516, SE-75120 Uppsala, Sweden..
    Sychugov, Ilya
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Ottosson, M.
    Uppsala Univ, Dept Chem, Angstrom Lab, Inorgan Chem, POB 538, SE-75121 Uppsala, Sweden..
    Primetzhofer, D.
    Uppsala Univ, Dept Phys & Astron, POB 516, SE-75120 Uppsala, Sweden..
    Moro, M. V.
    Uppsala Univ, Dept Phys & Astron, POB 516, SE-75120 Uppsala, Sweden..
    Linnros, Jan
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics.
    Hallén, Anders
    KTH, School of Information and Communication Technology (ICT).
    Luminescence of silicon nanoparticles from oxygen implanted silicon2018In: Materials Science in Semiconductor Processing, ISSN 1369-8001, E-ISSN 1873-4081, Vol. 86, p. 18-22Article in journal (Refereed)
    Abstract [en]

    Oxygen with a kinetic energy of 20 keV is implanted in a silicon wafer (100) at different fluences, followed by post-implantation thermal annealing (PIA) performed at temperatures ranging from 1000 to 1200 degrees C, in order to form luminescent silicon nanoparticles (SiNPs) and also to reduce the damage induced by the implantation. As a result of this procedure, a surface SiOx layer (with 0 < x < 2) with embedded crystalline Si nanoparticles has been created. The samples yield similar luminescence in terms of peak wavelength, lifetime, and absorption as recorded from SiNPs obtained by the more conventional method of implanting silicon into silicon dioxide. The oxygen implantation profile is characterized by elastic recoil detection (ERD) technique to obtain the excess concentration of Si in a presumed SiO2 environment. The physical structure of the implanted Si wafer is examined by grazing incidence X-ray diffraction (GIXRD). Photoluminescence (PL) techniques, including PL spectroscopy, time-resolved PL (TRPL), and photoluminescence excitation (PLE) spectroscopy are carried out in order to identify the PL origin. The results show that luminescent SiNPs are formed in a Si sample implanted by oxygen with a fluence of 2 x 10(17) atoms cm(-2) and PIA at 1000 degrees C. These SiNPs have a broad size range of 6-24 nm, as evaluated from the GIXRD result. Samples implanted at a lower fluence and/or annealed at higher temperature show only weak defect-related PL. With further optimization of the SiNP luminescence, the method may offer a simple route for integration of luminescent Si in mainstream semiconductor fabrication.

  • 57.
    Cong, Jiayan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Kinschel, Dominik
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. Dyenamo AB, Sweden.
    Daniel, Quentin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Safdari, Majid
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Gabrielsson, E.
    Chen, Hong
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Svensson, Per H.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. SP Process Development Forskargatan, Sweden.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. Dalian University of Technology (DUT), China.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Bis(1,1-bis(2-pyridyl)ethane)copper(i/II) as an efficient redox couple for liquid dye-sensitized solar cells2016In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 4, no 38, p. 14550-14554Article in journal (Refereed)
    Abstract [en]

    A new redox couple, [Cu(bpye)2]+/2+, has been synthesized, and applied in dye-sensitized solar cells (DSSCs). Overall efficiencies of 9.0% at 1 sun and 9.9% at 0.5 sun were obtained, which are considerably higher than those obtained for cells containing the reference redox couple, [Co(bpy)3]2+/3+. These results represent a record for copper-based complex redox systems in liquid DSSCs. Fast dye regeneration, sluggish recombination loss processes, faster electron self-exchange reactions and suitable redox potentials are the main reasons for the observed increase in efficiency. In particular, the main disadvantage of cobalt complex-based redox couples, charge-transport problems, appears to be resolved by a change to copper complex redox couples. The results make copper complex-based redox couples very promising for further development of highly efficient DSSCs.

  • 58.
    Crawford, James
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Neretnieks, Ivars
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Moreno, Luis
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Epistemic and aleatory uncertainty in recommended, generic rock K-d values used in performance assessment studies2006In: Scientific Basis for Nuclear Waste Management XXIX, WARRENDALE, PA: MATERIALS RESEARCH SOCIETY , 2006, Vol. 932, p. 251-258Conference paper (Refereed)
    Abstract [en]

    Over the past decade or so there has been an explosion in the number of sorption modelling approaches and applications of sorption modelling for understanding and predicting solute transport in natural systems. The most widely used and simplest of all models, however, is that employing a constant distribution coefficient (K-d) relating the sorbed concentration of a solute on a mineral surface and its aqueous concentration. There are a number of reasons why a constant partitioning coefficient is attractive to environmental modellers for predicting radionuclide retardation, and in spite of all the shortcomings and pitfalls associated with such an approach, it remains the leitmotif of most performance assessment transport modelling. This paper examines the scientific basis underpinning the K-d-approach and its broad defensibility in a performance assessment framework. It also examines sources of epistemic and aleatory uncertainty that undermine confidence in K-d-values reported in the open literature. The paper focuses particularly upon the use of so-called "generic" data for generalised rock types that may not necessarily capture the full material property characteristics of site-specific materials. From the examination of recent literature data, it appears that there are still a number of outstanding issues concerning interpretation of experimental laboratory data that need to be considered in greater detail before concluding that the recommended values used in performance assessments are indeed conservative.

  • 59.
    Csontos, Botond
    KTH, School of Chemical Science and Engineering (CHE).
    Development of a method to measure “soft particles” in the fuel2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    As environmental awareness raises the expectations to reduce emission of modern diesel engines are growing as well. Fuel diversity and the advanced injector systems requires even more attention on an ever existing problem which is called nozzle hole fouling. Recent literature and observations at Scania indicate the phenomena is connected to fuel filter plugging caused by metal carboxyl contaminants through the formation of “soft particles”.

    This report begins with a literature review about the nature of agglomerates in biodiesel. Followed by the evaluation of six particle sizing equipment. This include one ensemble technique based on Brownian motion, namely dynamic light scattering. The remaining five techniques are single particle counters, including a high speed camera system, light blocking system, Nano tracking analysis and two different approaches using light microscope. To characterise the structure and chemical components of the particles SEM, EDX, FT-IR and ICP-OES were used.

    From the above mentioned methods optical microscopy was chosen to be the best method to evaluate the particle distribution. The main reasons for this is the ability to measure particles in the solution in the desired size range and the possibility to couple it with a Raman spectrometer, providing possibilities for future studies.

    Besides finding the best technique to measure the particles, a secondary result is the negation of Zinc-neodecanoate creating particles in the fuel. It opposes the assumption made in the literature about filter blocking, and it finds the need for deeper understanding of the nature of soft particles.

  • 60. Cuartero, Maria
    et al.
    Acres, Robert G.
    Bradley, John
    Jarolimova, Zdenka
    Wang, Lu
    Bakker, Eric
    Crespo, Gaston A.
    University of Geneva, Switzerland.
    De Marco, Roland
    Electrochemical Mechanism of Ferrocene-Based Redox Molecules in Thin Film Membrane Electrodes2017In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 238, p. 357-367Article in journal (Refereed)
    Abstract [en]

    Cyclic voltammetry (CV) in chloride-based aqueous electrolytes of ferrocene molecule doped thin membranes (similar to 200 nm in thickness) on glassy carbon (GC) substrate electrodes, both plasticized poly (vinyl chloride) (PVC) and unplasticized poly(methyl methacrylate)/poly(decyl methacrylate) (PMMA-PDMA) membranes, has shown that the electrochemical oxidation behavior is irreversible due most likely to degradation of ferrocene at the buried interface (GC vertical bar membrane). Furthermore, CV of the ferrocene molecules at GC electrodes in organic solvents employing chloride-based and chloride-free organic electrolytes has demonstrated that the chloride anion is inextricably linked to this irreversible ferrocene oxidation electrochemistry. Accordingly, we have explored the electrochemical oxidation mechanism of ferrocene-based redox molecules in thin film plasticized and unplasticized polymeric membrane electrodes by coupling synchrotron radiation-X-ray photoelectron spectroscopy (SR-XPS) and near edge X-ray absorption fine structure (NEXAFS) with argon ion sputtering to depth profile the electrochemically oxidized thin membrane systems. With the PVC depth profiling studies, it was not possible to precisely study the influence of chloride on the ferrocene reactivity due to the high atomic ratio of chloride in the PVC membrane; however, the depth profiling results obtained with a chlorine-free polymer (PMMA-PDMA) provided irrefutable evidence for the formation of a chloride-based iron product at the GC| PMMA-PDMA interface. Finally, we have identified conditions that prevent the irreversible conversion of ferrocene by utilizing a high loading of redox active reagent and/or an ionic liquid (IL) membrane plasticizer with high ionicity that suppresses the mass transfer of chloride.

  • 61. Cui, Y.
    et al.
    Liu, Q.
    Wang, Lihui
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Ding, W.
    Wang, Xi Vincent
    KTH, School of Industrial Engineering and Management (ITM), Production Engineering.
    Liu, Y.
    Li, D.
    Research on milling temperature measuring tool embedded with NiCr/NiSi thin film thermocouple2018In: 51st CIRP Conference on Manufacturing Systems, Elsevier, 2018, Vol. 72, p. 1457-1462Conference paper (Refereed)
    Abstract [en]

    In order to measure the milling area temperature in-situ, the milling tool embedded with NiCr/NiSi thin film thermocouple (TFTC) is prepared. TFTC capable well temperature performance is embedded on the tool tip by successively depositing SiO2 insulating film, NiCr/NiSi thermoelectric film, and SiO2 protective film. Surface morphology and thin film properties are confirmed to achieve expectation by means of TEM and SEM. Imitation reflects that TFTC abrasion has minor effect on dynamic and static characteristic. The in-situ milling area temperature is successfully detected by TFTC temperature measuring tool in field test.

  • 62. da Silva, A. F.
    et al.
    Pepe, I.
    Gole, J. L.
    Tomas, S. A.
    Palomino, R.
    de Azevedo, W. M.
    da Silva, E. F.
    Ahuja, R.
    Persson, Clas
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Applied Material Physics.
    Optical properties of in situ doped and undoped titania nanocatalysts and doped titania sol-gel nanofilms2006In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 252, no 15, p. 5365-5367Article in journal (Refereed)
    Abstract [en]

    In this paper we present spectroscopic properties of doped and undoped titanium dioxide (TiO2) as nanofilms prepared by the sol-gel process with rhodamine 6G doping and studied by photoacoustic absorption, excitation and emission spectroscopy. The absorption spectra of TiO2 thin films doped with rhodamine 6G at very low concentration during their preparation show two absorption bands, one at 2.3 eV attributed to molecular dimmer formation, which is responsible for the fluorescence quenching of the sample and the other at 3.0 eV attributed to TiO2 absorption, which subsequently yields a strong en-fission band at 600 nm. The electronic band structure and optical properties of the rutile phase of TiO2 are calculated employing a fully relativistic, full-potential, linearized, augmented plane-wave (FPLAPW) method within the local density approximation (LDA). Comparison of this calculation with experimental data for TiO2 films prepared for undoped sol-gels and by sputtering is performed.

  • 63.
    Dahlstedt, Emma
    et al.
    KTH, Superseded Departments, Chemistry.
    Hellberg, Jonas S. E.
    KTH, Superseded Departments, Chemistry.
    Petoral, R M
    Uvdal, K
    Synthesis of tetrathiafulvalenes suitable for self-assembly applications2004In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 14, no 1, p. 81-85Article in journal (Refereed)
    Abstract [en]

    A series of new tetrathiafulvalenes, with double alkylthiol or alkyldisulfide substitution, have been prepared with a synthetic procedure that allows variation of different substituents. The target compounds 6a-e and 15e-i are sparsely soluble in organic solvents, but TTFs 6d and 15g gave a relatively dense packed monolayer upon exposure to gold surfaces.

  • 64. D'Amario, Luca
    et al.
    Jiang, Roger
    Cappel, Ute B.
    Gibson, Elizabeth A.
    Boschloo, Gerrit
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Rensmo, Hakan
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Hammarstrom, Leif
    Tian, Haining
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Chemical and Physical Reduction of High Valence Ni States in Mesoporous NiO Film for Solar Cell Application2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 39, p. 33470-33477Article in journal (Refereed)
    Abstract [en]

    The most common material for dye-sensitized photocathodes is mesoporous NiO. We transformed the usual brownish NiO to be more transparent by reducing high valence Ni impurities. Two pretreatment methods have been used: chemical reduction by NaBH4 and thermal reduction by heating. The power conversion efficiency of the cell was increased by 33% through chemical treatment, and an increase in open-circuit voltage from 105 to 225 mV was obtained upon heat treatment. By optical spectroelectrochemistry, we could identify two species with characteristically different spectra assigned to Ni3+ and Ni4+. We suggest that the reduction of surface Ni3+ and Ni (4+) to Ni (2+) decreases the recombination reaction between holes on the NiO surface with the electrolyte. It also keeps the dye firmly on the surface, building a barrier for electrolyte recombination. This causes an increase in open-circuit photovoltage for the treated film.

  • 65. Davidsson, K. O.
    et al.
    Pettersson, J. B. C.
    Bellais, Michel
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Liliedahl, Truls
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Sjöström, Krister
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    The Pyrolysis Kinetics of a Single Wood Particle2008In: Progress in Thermochemical Biomass Conversion, Wiley-Blackwell, 2008, p. 1129-1142Chapter in book (Other academic)
    Abstract [en]

    Experimental results from birchwood and pinewood pyrolysis in a new single particle reactor are presented. Apparent lunetic parameters for the mass-loss of wood particles (5-800 mg) at temperatures from 300 to 860°C are determined. Kinetic parameters for the evolution of CO, CO2, H2O, H2 and CH4, are also established. The drylng process was examined and it was found that drying and pyrolysis increasingly overlap in time as temperature rises and that the overlap is substantial above 450 °C.

  • 66. Deligoz, H.
    et al.
    Baykal, A.
    Senel, M.
    Sozeri, H.
    Karaoglu, E.
    Toprak, Muhammet S.
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Synthesis and characterization of poly(1-vinyltriazole)-grafted superparamagnetic iron oxide nanoparticles2012In: Synthetic metals, ISSN 0379-6779, E-ISSN 1879-3290, Vol. 162, no 7-8, p. 590-597Article in journal (Refereed)
    Abstract [en]

    We reported on the synthesis and detailed physicochemical characterization of poly(1-vinyltriazole)-grafted iron oxide nanoparticles. Superparamagnetic iron oxide nanoparticles (SPION) were fabricated by gel-to-crystalline conversion method. Telomerization of poly(1-vinyltriazole) on iron oxide nanoparticles was achieved via silanization process. XRD analysis confirmed the crystalline phase as magnetite, and FT-IR analysis confirmed the presence of PVTri on nanoparticles. Particle morphology was observed to be polygonic, due to the synthesis process, while average size estimated from TEM micrographs is 7 nm. Agreement between crystallite size estimated from XRD and particle size from TEM affirms single crystalline character of these nanoparticles. Dependence of conductivity on temperature showed a strong evidence for thermally activated polarization mechanism. Temperature and frequency dependence of dielectric permittivity revealed interfacial polarization and temperature-assisted-reorganization effects. Magnetic evaluation showed non-saturation and superparamagnetic characteristics of nanoparticles as well as magnetic particles being single domains.

  • 67. Dev, A. S.
    et al.
    Kumar, D.
    Potdar, S.
    Pandit, P.
    Roth, Stephan Volkher
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology. Photon Science, DESY, Notkestrasse 85, Hamburg, Germany.
    Gupta, A.
    Portable mini-chamber for temperature dependent studies using small angle and wide angle x-ray scattering2018In: DAE Solid State Physics Symposium 2017, American Institute of Physics (AIP), 2018, Vol. 1942, article id 080057Conference paper (Refereed)
    Abstract [en]

    The present work describes the design and performance of a vacuum compatible portable mini chamber for temperature dependent GISAXS and GIWAXS studies of thin films and multilayer structures. The water cooled body of the chamber allows sample annealing up to 900 K using ultra high vacuum compatible (UHV) pyrolytic boron nitride heater, thus making it possible to study the temperature dependent evolution of structure and morphology of two-dimensional nanostructured materials. Due to its light weight and small size, the chamber is portable and can be accommodated at synchrotron facilities worldwide. A systematic illustration of the versatility of the chamber has been demonstrated at beamline P03, PETRA-III, DESY, Hamburg, Germany. Temperature dependent grazing incidence small angle x-ray scattering (GISAXS) and grazing incidence wide angle x-ray scattering (GIWAXS) measurements were performed on oblique angle deposited Co/Ag multilayer structure, which jointly revealed that the surface diffusion in Co columns in Co/Ag multilayer enhances by increasing temperature from RT to ∼573 K. This results in a morphology change from columnar tilted structure to densely packed morphological isotropic multilayer

  • 68.
    Dev Choudhury, Bikash
    et al.
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Semiconductor Materials, HMA.
    Anand, Srinivasan
    Rapid thermal annealing treated spin-on doped antireflective radial junction Si nanopillar solar cell2017In: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 25, no 8, p. A200-A207Article in journal (Refereed)
    Abstract [en]

    Radial junction nanopillar Si solar cells are interesting for cost effective efficiency improvement. Here, we address a convenient top-down fabrication of Si nanopillar solar cells using spin-on doping and rapid thermal annealing (RTA) for conformal PN junction formation. Broadband suppressed reflection as low as an average of 5% in the 300-1100 nm wavelength range and un-optimized cell efficiency of 7.3% are achieved. The solar cell performance can be improved by optimization of spin-on-doping and suitable surface passivation. Overall, the all RTA processed, spin-on doped nanopillar radial junction solar cell shows a very promising route for low cost and high efficiency thin film solar cell perspectives.

  • 69. Dobrota, Ana S.
    et al.
    Pasti, Igor A.
    Mentus, Slavko V.
    Johansson, Börje
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Uppsala University, Sweden.
    Skorodumova, Natalia V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Uppsala University, Sweden.
    Functionalized graphene for sodium battery applications: the DFT insights2017In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 250, p. 185-195Article in journal (Refereed)
    Abstract [en]

    Considering the increasing interest in the use of graphene-based materials for energy conversion and storage applications, we have performed a DFT study of Na interaction with doped graphene, both in non-oxidized and oxidized forms. Oxidation seems to play the crucial role when it comes to the interaction of doped graphene materials with sodium. The dopants act as attractors of OH groups, making the material prone to oxidation, and therefore altering its affinity towards Na. In some cases, this can result in hydroxide or water formation - an irreversible change lethal for battery performance. Our results suggest that one should carefully control the oxidation level of doped graphene-based materials if they are to be used as sodium battery electrode materials as the optimal oxidation level depends on the dopant type.

  • 70. Dobrota, Ana S.
    et al.
    Pasti, Igor A.
    Skorodumova, Natalia V.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering. Uppsala University, Sweden.
    Oxidized graphene as an electrode material for rechargeable metal-ion batteries - a DFT point of view2015In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 176, p. 1092-1099Article in journal (Refereed)
    Abstract [en]

    In line with a growing interest in the use of graphene-based materials for energy storage applications and active research in the field of rechargeable metal-ion batteries we have performed a DFT based computational study of alkali metal atoms (Li, Na and K) interaction with an oxidized graphene. The presence of oxygen surface groups (epoxy and hydroxyl) alters the chemisorption properties of graphene. In particular, we observe that the epoxy groups are redox active and enhance the alkali metal adsorption energies by a factor of 2 or more. When an alkali metal atom interacts with hydroxyl-graphene the formation of metal-hydroxide is observed. In addition to a potential boost of metal ion storage capability, oxygen functional groups also prevent the precipitation of the metal phase. By simulating lithiation/de-lithiation process on epoxy-graphenes, it was concluded that the oxidized graphene can undergo structural changes during battery operation. Our results suggest that the content and the type of oxygen surface groups should be carefully tailored to maximize the performance of metal-ion batteries. This is mainly related to the control of the oxidation level in order to provide enough active centers for metal ion storage while preserving sufficient electrical conductivity.

  • 71.
    Doe, Maofeng
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Multiscale Materials Modelling.
    Persson, Clas
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Multiscale Materials Modelling. Department of Physics, University of Oslo, Norway .
    Analysis of the Semi local States in ZnO-InN Compounds2014In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 14, no 10, p. 4937-4943Article in journal (Refereed)
    Abstract [en]

    ZnO alloys are extensively explored for the developments of optoelectronics. In this work we analyze the rather unconventional type of ZnO-based compound ZnOX (ZnO)(1y)Xy with X = InN. The compound forms alloy with ZnO and/or assembles cluster structures in the ZnO host. Importantly, this type of alloy benefits from being isovalent which implies a more stable crystalline structure, and at the same time it benefits from the oxynitride anion-alloying that alters the optoelectronic properties. Theoretical studies reveal that incorporating InN in ZnO strongly narrows the fundamental band gap energy Eg. For example, the (ZnO)(0.875)(InN)(0.125) alloy has the gap energy E-g = 2.20 eV = E-g(ZnO) 1.14 eV. The origin of this effect is a hybridization of the anion N 2p-like and O 2p-like orbitals. Intriguingly, the presence of InN nanoclusters enhances this effect and narrows the gap further, and moreover, the nanostructured configurations show more disperse energy distribution of the hybridized anion states compared with the random alloy. Nanoclustering affects the ZnO host more compared to structures with more random distribution of the InN dimers. On the basis of the different characters of the alloys and the nanostructures, we conclude that fine-tuned synthesizing of the (ZnO)(1-y)(InN)(y) alloys can be beneficial for a variety of novel nanosystems for optoelectronic and photoelectrochemical applications.

  • 72.
    Duval, Antoine
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Vilaplana, Francisco
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Biotechnology (BIO), Glycoscience.
    Crestini, Claudia
    Lawoko, Martin
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Solvent screening for the fractionation of industrial kraft lignin2016In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 70, no 1, p. 11-20Article in journal (Refereed)
    Abstract [en]

    The polydispersity of commercially available kraft lignins (KLs) is one of the factors limiting their applications in polymer-based materials. A prerequisite is thus to develop lignin fractionation strategies compatible with industrial requirements and restrictions. For this purpose, a solvent-based lignin fractionation technique has been addressed. The partial solubility of KL in common industrial solvents compliant with the requirements of sustainable chemistry was studied, and the results were discussed in relation to Hansen solubility parameters. Based on this screening, a solvent sequence is proposed, which is able to separate well-defined KL fractions with low polydispersity.

  • 73.
    Ekeroth, Sebastian
    et al.
    Linkoping Univ, Dept Phys, SE-58183 Linkoping, Sweden..
    Munger, E. Peter
    Linkoping Univ, Dept Phys, SE-58183 Linkoping, Sweden..
    Boyd, Robert
    Linkoping Univ, Dept Phys, SE-58183 Linkoping, Sweden..
    Ekspong, Joakim
    Umea Univ, Dept Phys, SE-90187 Umea, Sweden..
    Wagberg, Thomas
    Umea Univ, Dept Phys, SE-90187 Umea, Sweden..
    Edman, Ludvig
    Umea Univ, Dept Phys, SE-90187 Umea, Sweden..
    Brenning, Nils
    KTH, School of Electrical Engineering and Computer Science (EECS), Space and Plasma Physics. Linkoping Univ, Dept Phys, SE-58183 Linkoping, Sweden.
    Helmersson, Ulf
    Linkoping Univ, Dept Phys, SE-58183 Linkoping, Sweden..
    Catalytic Nanotruss Structures Realized by Magnetic Self-Assembly in Pulsed Plasma2018In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 18, no 5, p. 3132-3137Article in journal (Refereed)
    Abstract [en]

    Tunable nanostructures that feature a high surface area are firmly attached to a conducting substrate and can be fabricated efficiently over significant areas, which are of interest for a wide variety of applications in, for instance, energy storage and catalysis. We present a novel approach to fabricate Fe nanoparticles using a pulsed-plasma process and their subsequent guidance and self-organization into well-defined nanostructures on a substrate of choice by the use of an external magnetic field. A systematic analysis and study of the growth procedure demonstrate that nondesired nanoparticle agglomeration in the plasma phase is hindered by electrostatic repulsion, that a polydisperse nanoparticle distribution is a consequence of the magnetic collection, and that the formation of highly networked nanotruss structures is a direct result of the polydisperse nanoparticle distribution. The nanoparticles in the nanotruss are strongly connected, and their outer surfaces are covered with a 2 nm layer of iron oxide. A 10 mu m thick nanotruss structure was grown on a lightweight, flexible and conducting carbon-paper substrate, which enabled the efficient production of H-2 gas from water splitting at a low overpotential of 210 mV and at a current density of 10 mA/cm(2).

  • 74. El-Sayed, R.
    et al.
    Ye, F.
    Asem, Heba
    KTH, School of Engineering Sciences (SCI), Applied Physics, Functional Materials, FNM.
    Ashour, Radwa
    KTH, School of Engineering Sciences (SCI), Applied Physics, Functional Materials, FNM.
    Zheng, W.
    Muhammed, Mamoun
    KTH, School of Engineering Sciences (SCI), Applied Physics, Functional Materials, FNM. Alexandria University, Egypt.
    Hassan, M.
    Importance of the surface chemistry of nanoparticles on peroxidase-like activity2017In: Biochemical and Biophysical Research Communications - BBRC, ISSN 0006-291X, E-ISSN 1090-2104, Vol. 491, no 1, p. 15-18Article in journal (Refereed)
    Abstract [en]

    We report the studies on origin of peroxidase-like activity for gold nanoparticles, as well as the impact from morphology and surface charge of nanoparticles. For this purpose, we have synthesized hollow gold nanospheres (HAuNS) and gold nanorods (AuNR) with different morphology and surface chemistry to investigate their influence on the catalytic activity. We found that citrate-capped HAuNS show catalyzing efficiency in oxidation reaction of 3,3′,5,5′-tetramethylbenzidine (TMB) by hydrogen peroxide (H2O2) and it is superior to that of cetyltrimethylammonium bromide (CTAB)-capped AuNR. The kinetics of catalytic activities from HAuNS and AuNR were respectively studied under varied temperatures. The results indicated that surface chemistry rather than morphology of nanoparticles plays an important role in the catalytic reaction of substrate. Furthermore, influencing factors such as pH, amount of nanoparticle and H2O2 concentration were also investigated on HAuNS-catalyzed system. The great impact of nanoparticle surface properties on catalytic reactions makes a paradigm in constructing nanozymes as peroxidase mimic for sensing application.

  • 75.
    Engström, Joakim
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Brett, Calvin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Malmström, Eva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Roth, Stephan V.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Film formation of soft and rigid PISA‐latexes –analysis of thin films using GISAXSManuscript (preprint) (Other academic)
  • 76.
    Engström, Joakim
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Jimenez, Andrew
    Columbia University.
    Malmström, Eva
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Kumar, Sanat
    Columbia University.
    Nanoparticle Rearrangement Under Stress inCellulose Nanofibrils Networks using in situ SAXSMeasurements During Tensile TestingManuscript (preprint) (Other academic)
  • 77.
    Erik, Johansson
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Molecular Interactions in Thin Films of Biopolymers, Colloids and Synthetic Polyelectrolytes2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The development of the layer-by-layer (LbL) technique has turned out to be an efficient way to physically modify the surface properties of different materials, for example to improve the adhesive interactions between fibers in paper. The main objective of the work described in this thesis was to obtain fundamental data concerning the adhesive properties of wood biopolymers and LbL films, including the mechanical properties of the thin films, in order to shed light on the molecular mechanisms responsible for the adhesion between these materials.

    LbLs constructed from poly(allylamine hydrochloride) (PAH)/poly(acrylic acid) (PAA), starch containing LbL films, and LbL films containing nanofibrillated cellulose (NFC) were studied with respect to their adhesive and mechanical properties. The LbL formation was studied using a combination of stagnation point adsorption reflectometry (SPAR) and quartz crystal microbalance with dissipation (QCM-D) and the adhesive properties of the different LbL films were studied in water using atomic force microscopy (AFM) colloidal probe measurements and under ambient conditions using the Johnson-Kendall-Roberts (JKR) approach. Finally the mechanical properties were investigated by mechanical buckling and the recently developed SIEBIMM technique (strain-induced elastic buckling instability for mechanical measurements).

    From colloidal probe AFM measurements of the wet adhesive properties of surfaces treated with PAH/PAA it was concluded that the development of strong adhesive joints is very dependent on the mobility of the polyelectrolytes and interdiffusion across the interface between the LbL treated surfaces to allow for polymer entanglements.

    Starch is a renewable, cost-efficient biopolymer that is already widely used in papermaking which makes it an interesting candidate for the formation of LbL films in practical systems. It was shown, using SPAR and QCM-D, that LbL films can be successfully constructed from cationic and anionic starches on silicon dioxide and on polydimethylsiloxane (PDMS) substrates. Colloidal probe AFM measurements showed that starch LbL treatment have potential for increasing the adhesive interaction between solid substrates to levels beyond those that can be reached by a single layer of cationic starch. Furthermore, it was shown by SIEBIMM measurements that the elastic properties of starch-containing LbL films can be tailored using different nanoparticles in combination with starch.

    LbL films containing cellulose I nanofibrils were constructed using anionic NFC in combination with cationic NFC and poly(ethylene imine) (PEI) respectively. These NFC films were used as cellulose model surfaces and colloidal probe AFM was used to measure the adhesive interactions in water. Furthermore, PDMS caps were successfully coated by LbL films containing NFC which enabled the first known JKR adhesion measurements between cellulose/cellulose, cellulose/lignin and cellulose/glucomannan. The measured adhesion and adhesion hysteresis were similar for all three systems indicating that there are no profound differences in the interaction between different wood biopolymers. Finally, the elastic properties of PEI/NFC LbL films were investigated using SIEBIMM and it was shown that the stiffness of the films was highly dependent on the relative humidity.

  • 78.
    Erlandsson, Johan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Duran, Veronica Lopez
    Granberg, Hjalmar
    Innventia AB.
    Sandberg, Mats
    Acreo Swedish ICT AB.
    Larsson, Per A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Macro- and mesoporous nanocellulose beads for use in energy storage devices2016In: APPLIED MATERIALS TODAY, ISSN 2352-9407, Vol. 5, p. 246-254Article in journal (Refereed)
    Abstract [en]

    Chemically cross-linked, wet-stable cellulose nanofibril (CNF) aerogel beads were fabricated using a novel procedure. The procedure facilitated controlled production of millimetre-sized CNF aerogel beads without freeze-drying or critical point drying, while still retaining a highly porous structure with low density. The aerogel beads were mechanically robust in the dry state, supporting loads of 1.3 N at 70% compression, even after being soaked in water and re-dried. Furthermore, they displayed both a good stability in water and a remarkably good shape recovery after wet compression. Owing to the stability in water, the entire surface of the highly porous aerogel beads could be successfully functionalized with polyelectrolytes and carboxyl-functionalized single-wall carbon nanotubes (CF-SWCNTs) using the Layer-by-Layer technique, introducing a significant electrical conductivity (1.6 mS/cm) to the aerogel beads. The functionalized, electrically conducting aerogel beads could carry as much as 2 kA/cm(2) and act as electrodes in a supercapacitor displaying a stabilized charge storage capacity of 9.8 F/g after 50 charging-discharging cycles.

  • 79.
    Erlandsson, Johan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Francon, Hugo
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Marais, Andrew
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology.
    Granberg, Hjalmar
    RISE Bioecon, Papermaking & Packaging, Box 5604, SE-11486 Stockholm, Sweden..
    Wågberg, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Cross-Linked and Shapeable Porous 3D Substrates from Freeze-Linked Cellulose Nanofibrils2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 2, p. 728-737Article in journal (Refereed)
    Abstract [en]

    Chemically cross-linked highly porous nano cellulose aerogels with complex shapes have been prepared using a freeze-linking procedure that avoids common post activation of cross-linking reactions and freeze-drying. The aerogel shapes ranged from simple geometrical three-dimensional bodies to swirls and solenoids. This was achieved by molding or extruding a periodate oxidized cellulose nanofibril (CNF) dispersion prior to chemical cross-linking in a regular freezer or by reshaping an already prepared aerogel by plasticizing the structure in water followed by reshaping and locking the aerogel into its new shape. The new shapes were most likely retained by new cross-links formed between CNFs brought into contact by the deformation during reshaping. This self-healing ability to form new bonds after plasticization and redrying also contributed to the mechanical resilience of the aerogels, allowing them to be cyclically deformed in the dry state, reswollen with water, and redried with good retention of mechanical integrity. Furthermore, by exploiting the shapeability and available inner structure of the aerogels, a solenoid-shaped aerogel with all surfaces coated with a thin film of conducting polypyrrole was able to produce a magnetic field inside the solenoid, demonstrating electromagnetic properties. Furthermore, by biomimicking the porous interior and stiff exterior of the beak of a toucan bird, a functionalized aerogel was created by applying a 300 mu m thick stiff wax coating on its molded external surfaces. This composite material displayed a 10-times higher elastic modulus compared to that of the plain aerogel without drastically increasing the density. These examples show that it is possible to combine advanced shaping with functionalization of both the inner structure and the surface of the aerogels, radically extending the possible use of CNF aerogels.

  • 80.
    Evangelopoulos, Panagiotis
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Kantarelis, Efthymios
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Experimental investigation of the influence of reaction atmosphere on the pyrolysis of printed circuit boards2017In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 204, p. 1065-1073Article in journal (Refereed)
    Abstract [en]

    Printed circuit boards (PCB) are one of the most challenging fractions of waste electrical and electronic equipment (WEEE) in terms of recycling due to their complexity and diversity. Pyrolysis seems to be a promising alternative for production of energy carriers from its organic fraction with simultaneous recovery of metals. Reaction atmosphere is among the process parameters that affects the thermal decomposition as well as the products’ formation and distribution. In this study, the decomposition of two different PCB fractions in inert and steam atmospheres has been investigated by means of thermogravimetric analysis (TGA) and lab scale fixed bed reactor experiments. It was found that the decomposition of the tested materials in steam atmosphere starts at lower temperatures and proceeds slower compared to the N2 atmosphere. Moreover, a two-step decomposition has been observed on the PCB sockets fraction due to the fact that high amount of antimony oxide was present, a common additive for improving the flame retardancy, which have been also observed on previous studies (Wu et al., 2014). The presence of steam influence the pyrolysis gas composition and promotes additional vaporisation of antimony as verified by powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). Finally, the liquid fraction has been qualitatively analysed using a GC/MS in order to determine the brominated compounds as well as other compounds that are produced from this process.

  • 81. Evertsson, J.
    et al.
    Bertram, F.
    Zhang, Fan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Rullik, L.
    Merte, L. R.
    Shipilin, M.
    Soldemo, Markus
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Ahmadi, Sareh
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Vinogradov, N.
    Carla, F.
    Weissenrieder, Jonas
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Götelid, Mats
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Material Physics, MF.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Mikkelsen, A.
    Nilsson, J. -O
    Lundgren, E.
    The thickness of native oxides on aluminum alloys and single crystals2015In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 349, p. 826-832Article in journal (Refereed)
    Abstract [en]

    We present results from measurements of the native oxide film thickness on four different industrial aluminum alloys and three different aluminum single crystals. The thicknesses were determined using X-ray reflectivity, X-ray photoelectron spectroscopy, and electrochemical impedance spectroscopy. In addition, atomic force microscopy was used for micro-structural studies of the oxide surfaces. The reflectivity measurements were performed in ultra-high vacuum, vacuum, ambient, nitrogen and liquid water conditions. The results obtained using X-ray reflectivity and X-ray photoelectron spectroscopy demonstrate good agreement. However, the oxide thicknesses determined from the electrochemical impedance spectroscopy show a larger discrepancy from the above two methods. In the present contribution the reasons for this discrepancy are discussed. We also address the effect of the substrate type and the presence of water on the resultant oxide thickness.

  • 82.
    Fall, Andreas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Lindström, Stefan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Sprakel, Joris
    School of Engineering and Applied Sciences, Harvard University, Cambridge, USA.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Microstructure control of physically cross-linked nanocellulose gels for biocomposite templatesManuscript (preprint) (Other academic)
  • 83.
    Fall, Andreas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Biofibre Materials Centre, BiMaC.
    Lindström, Stefan
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation.
    Sundman, Ola
    Department of Forest Products Technology, Aalto, Finland.
    Ödberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Colloidal Stability of Aqueous Nanofibrillated Cellulose Dispersions2011In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 27, no 18, p. 11332-11338Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibrils constitute an attractive raw material for carbon-neutral, biodegradable, nanostructured materials. Aqueous suspensions of these nanofibrils are stabilized by electrostatic repulsion arising from deprotonated carboxyl groups at the fibril surface. In the present work, a new model is developed for predicting colloidal stability by considering deprotonation and electrostatic screening. This model predicts the fibril-fibril interaction potential at a given pH in a given ionic strength environment. Experiments support the model predictions that aggregation is induced by decreasing the pH, thus reducing the surface charge, or by increasing the salt concentration. It is shown that the primary mechanism for aggregation upon the addition of salt is the surface charge reduction through specific interactions of counterions with the deprotonated carboxyl groups, and the screening effect of the salt is of secondary importance.

  • 84.
    Fan, Liangdong
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Ma, Ying
    Wang, Xiaodi
    KTH, School of Information and Communication Technology (ICT), Materials- and Nano Physics, Functional Materials, FNM.
    Singh, Manish
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Zhu, Bin
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Heat and Power Technology.
    Understanding the electrochemical mechanism of the core-shell ceria-LiZnO nanocomposite in a low temperature solid oxide fuel cell2014In: Journal of Materials Chemistry A, ISSN 2050-7488, Vol. 2, no 15, p. 5399-5407Article in journal (Refereed)
    Abstract [en]

    Ceria based solid solutions have been considered some of the best candidates to develop intermediate/low temperature solid oxide fuel cells (IT/LT-SOFCs, 600-800 degrees C). However, the barrier to commercialization has not been overcome even after numerous research activities due to its inherent electronic conduction in a reducing atmosphere and inadequate ionic conductivity at low temperatures. The present work reports a new type of all-oxide nanocomposite electrolyte material based on a semiconductor, Li-doped ZnO (LixZnO), and an ionic conductor, samarium doped ceria (SDC). This electrolyte exhibits superionic conductivity (>0.1 S cm(-1) over 300 degrees C), net-electron free and excellent electrolytic performances (400-630 mW cm(-2)) between 480 and 550 degrees C. Particularly, defects related to interfacial conduction and the intrinsic and extrinsic properties of ions are analysed. An internal or interfacial redox process on two-phase particles is suggested as a powerful methodology to overcome the internal short-circuit problem of ceria-based single phase materials and to develop new advanced materials for energy related applications. The combination of the above promising features makes the SDC-LiZnO nanocomposite a promising electrolyte for LTSOFCs.

  • 85. Fan, Liangdong
    et al.
    Zhu, Bin
    KTH, School of Electrical Engineering and Computer Science (EECS), Media Technology and Interaction Design, MID.
    Su, Pei-Chen
    He, Chuanxin
    Nanomaterials and technologies for low temperature solid oxide fuel cells: Recent advances, challenges and opportunities2018In: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 45, p. 148-176Article, review/survey (Refereed)
    Abstract [en]

    Solid oxide fuel cells (SOFCs) show considerable promise for meeting the current ever-increasing energy demand and environmental sustainability requirements because of their high efficiency, low environmental impact, and distinct fuel diversity. In the past few decades, extensive R&D efforts have been focused on lowering operational temperatures in order to decrease the system (stack and balance-of-plant) cost and improve the longevity of operationally useful devices of commercial relevance. Nanomaterials and related nanotechnologies have the potential to improve SOFC performance because of their advantageous functionalities, namely, their enlarged surface area and unique surface and interface properties compared to their microscale analogs. Recently, the use of nanomaterials has increased rapidly, as reflected by the exponential growth in the number of publications since 2002. In this work, we present a comprehensive summary of nanoparticles, nano-thin films and nanocomposites with different crystal phases, morphologies, microstructures, electronic properties, and electrochemical performances for low temperature SOFCs (LT-SOFCs), with focus on efforts to enhance electrical efficiency, to induce novel fundamental properties that are inaccessible in microcrystalline materials, and to promote the commercialization of LT-SOFCs. Recent progress in the applications of many classically or newly chemical and physical nanomaterials and nanofabrication techniques, such as thin film vacuum deposition, impregnation, electrospinning, spark plasma sintering, hard-and soft-template methods, and in-situ nanoparticle surface exsolution are also thoroughly described. The technological and scientific advantages and limitations related to the use of nanomaterials and nanotechnologies are highlighted, along with our expectations for future research within this emerging field.

  • 86.
    Fischer, Andreas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Sokka, Ilia
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Belova, Liubov
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Engineering Material Physics.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Synthesis, structure, and magnetic properties of some layered compounds based on long-chain sulfonium cations and complex cobalt and copper anions2013In: Zeitschrift für Anorganische und Allgemeines Chemie, ISSN 0044-2313, E-ISSN 1521-3749, Vol. 639, no 14, p. 2613-2617Article in journal (Refereed)
    Abstract [en]

    Two new materials of the composition ({CH3(CH2) 15(CH3)2S}+)2[CoBr 4]2- (1) and ({CH3(CH2) 15(CH3)2S}+)2[CuBr 4]2- (2 and 3), of which the latter exists in two polymorphs, were synthesized. The materials display the synthetically targeted structures, comprising of layers of complex metal ions and layers of long-chain sulfonium cations. The crystal structures of the materials were determined. The interlayer distances are around 24 Å, with metal-metal distances about 8 Å. The magnetic properties of 1 were investigated, and the material is paramagnetic. ({CH3(CH2)15(CH3) 2S}+)2[CuBr4]2 is polymorphic. Both polymorphs crystallize with triclinic symmetry.

  • 87.
    Fornara, Andrea
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Magnetic nanostructured materials for advanced bio-applications2008Licentiate thesis, comprehensive summary (Other scientific)
    Abstract [en]

    In the recent years, nanostructured magnetic materials and their use in biomedical and biotechnological applications have received a lot of attention. In this thesis, we developed tailored magnetic nanoparticles for advanced bio-applications, such as direct detection of antibodies in biological samples and stimuli responsive drug delivery system.

    For sensitive and selective detection of biomolecules, thermally blocked iron oxide nanoparticles with specific magnetic properties are synthesized by thermal hydrolysis to achieve a narrow size distribution just above the superparamagnetic limit.  The prepared nanoparticles were characterized and functionalized with biomolecules for use in a successful biosensor system. We have demonstrated the applicability of this type of nanoparticles for the detection of Brucella antibodies as model compound in serum samples and very low detection limits were achieved (0.05 mg/mL).

    The second part is concerning an in-depth investigation of the evolution of the thermally blocked magnetic nanoparticles. In this study, the formation of the nanoparticles at different stages during the synthesis was investigated by high resolution electron microscopy and correlated to their magnetic properties.  At early stage of the high temperature synthesis, small nuclei of 3.5 nm are formed and the particles size increases successively until they reach a size of 17-20 nm. The small particles first exhibit superparamagnetic behavior at the early stage of synthesis and then transform to thermally blocked behavior as their size increases and passes the superparamagnetic limit.

    The last section of the Thesis is related to the development of novel drug delivery system based on magnetically controlled release rate. The system consists of hydrogel of Pluronic FP127 incorporating superparamagnetic iron oxide nanoparticles to form a ferrogel. The sol to gel formation of the hydrogel could be tailored to be solid at body temperature and thus have the ability to be injected inside living biological tissues.

    In order to evaluate the drug loading and release, the hydrophobic drug indomethacin was selected as a model compound. The drug could be loaded in the ferrogel owning to the oil in water micellar structure. We have studied the release rate from the ferrogel in the absence and presence of magnetic field. We have demonstrated that the drug release rate can be significantly enhanced by use of external magnetic field decreasing the half time of the release to more than 50% (from 3200 to 1500 min) upon the application of the external magnetic field.

    This makes the developed ferrogel a very promising drug delivery system that does not require surgical implant procedure for medical treatment and gives the possibility of enhancing the rate of release by external magnetic field.

  • 88.
    Forslund, Mattias
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Pan, Jinshan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Hosseinpour, Saman
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Zhang, Fan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Johnson, Magnus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Claesson, Per
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Leygraf, Christofer
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    The atmospheric corrosion inhibition of octadecanethiol adsorbed on two brass alloys exposed to humidified air with formic acidManuscript (preprint) (Other academic)
    Abstract [en]

    Self-assembled monolayers of octadecanethiol (ODT) have previously shown to provide excellent corrosion inhibition on copper exposed to humidified air containing formic acid - mimicking indoor atmospheric corrosion. ODT layers are, however, much less efficient corrosion inhibitors for zinc. In this work we elucidate the possibility of using ODT monolayers to inhibit corrosion of brass. We find that ODT provides equally good corrosion inhibition of single-phase Cu20Zn as of pure copper, retarding the transport of corrosion stimulators to the brass surface. On double-phase Cu40Zn, however, local galvanic effects lead to less efficient corrosion inhibition and more corrosion products than on Cu20Zn.

  • 89.
    Furberg, Richard
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Li, Shanghua
    KTH, School of Information and Communication Technology (ICT), Microelectronics and Applied Physics, MAP.
    Palm, Björn
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Toprak, Muhammet
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Dendritically ordered nano-particles in a micro-porous structure for enhanced boiling2006In: Proceedings of 13th International Heat Transfer Conference, NAN-07, 2006, Vol. NAN-07Conference paper (Refereed)
    Abstract [en]

    Presented research is an experimental study of the pool boiling performance of copper surfaces enhanced with a newly developed structure. The enhanced surfaces were fabricated with an electrodeposition method where metallic nano-particles are formed and dendritically connected into an ordered micro-porous structure. To further alter the grain size of the dendritic branches, some surfaces underwent an annealing treatment. The tests were conducted with the test objects horizontally oriented and submerged in a refrigerant: R134A, at saturated conditions and at an absolute pressure of 4 bar. The heat flux varied between 0.1 and 10 W/cm2. The boiling performance of the enhanced surfaces was found to be dependent on controllable surface characteristics such as thickness of the structure and the interconnectivity of the grains in the dendritic branches. Temperature differences less than 0.3 °C and 1.5 °C at heat fluxes of 1 and 10 W/cm2 respectively have been recorded, corresponding to heat transfer coefficients up to 7.6 Wcm-2K-1. The micro-porous structure has been shown to facilitate high performance boiling, which is attributed to its high porosity (∼94%), a dendritically formed and exceptionally large surface area, and to a high density of well suited vapor escape channels (50 – 470 per mm2).

  • 90. Gane, P. A. C.
    et al.
    Ridgway, C. J.
    Lehtinen, E.
    Valiullin, Rustem
    KTH, Superseded Departments, Chemistry.
    Furo, Istvan
    KTH, Superseded Departments, Chemistry.
    Schoelkopf, J.
    Paulapuro, H.
    Daicic, J.
    Comparison of NMR cryoporometry, mercury intrusion porosimetry, and DSC thermoporosimetry in characterizing pore size distributions of compressed finely ground calcium carbonate structures2004In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 43, no 24, p. 7920-7927Article in journal (Refereed)
    Abstract [en]

    This work investigates for the first time how mercury intrusion porosimetry (MIP), NMR-based cryoporometry, and DSC-based thermoporosimetry compare in revealing the porous characteristics of ground calcium carbonate structures compacted over a range of pressures. The comparison is made using the same source samples throughout. MIP, a much-used method in the characterization of porous structures, has the drawback that the high pressure needed to intrude the mercury may either distort the skeletal porous structure of the sample, especially when compressible materials such as cellulose or binders/latex are present, or lead to a reduction in the measured number of large pores due to the shielding by smaller pores. These effects have previously been addressed using bulk modulus corrections and by modeling the structure permeability to account for the potential shielding. Cryoporometry gives detailed information about the pore size distribution of an imbibition saturated structure. Thermoporosimetry is a relatively new candidate in this field, and it yields both pore size distribution and pore volume. Currently it is somewhat limited in the pore size range detectable, but it is relevant to pigmented coatings. Its potential is identified for capturing the pores involved in the progress of imbibition before saturation is reached.

  • 91.
    Gao, Zhan
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Liu, Xingmin
    Bergman, Bill
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Ceramics.
    Zhao, Zhe
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Comparative study of Ce(0.85)Sm(0.075)Nd(0.075)O(2-delta) electrolyte synthesized by different routes2011In: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 509, no 35, p. 8720-8727Article in journal (Refereed)
    Abstract [en]

    In this work, four different methods, including polyvinyl alcohol (PVA)-assisted sol-gel process, polyethylene glycol (PEG)-assisted sol-gel process, citrate sol-gel process and oxalate coprecipitation process (OCP) are employed to synthesize the Sm and Nd co-doped ceria electrolyte with the composition of Ce(0.85)Sm(0.075)Nd(0.075)O(2-delta) (SNDC). The phase structure of the powders can be well indexed with the fluorite-type CeO(2) structure. The morphology of sintered samples indicates that the ceramics can be highly densified. The relative density and the average grain size vary with the synthesis processes and the sintering temperatures. The bulk conductivities are quite close and the OCP-SNDC yields highest grain-boundary conductivities and total conductivities. The results indicate that the OCP process for the powder synthesis results in higher relative density and conductivities, lower grain-boundary resistance and activation energy. Grain-boundary space charge potentials for different specimens are calculated based on the Mott-Schottky model. The synthesis process and sintering temperature have significant effect on the space charge potential and the specific grain-boundary conductivity. (C) 2011 Elsevier B.V. All rights reserved.

  • 92. Grybauskaite-Kaminskiene, Gintare
    et al.
    Ivaniuk, Khrystyna
    Bagdziunas, Gintautas
    Turyk, Pavlo
    Stakhira, Pavlo
    Baryshnikov, Gleb V.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Bohdan Khmelnytsky National University, Ukraine.
    Volyniuk, Dmytro
    Cherpak, Vladyslav
    Minaev, Boris F.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Bohdan Khmelnytsky National University, Ukraine.
    Hotra, Zenon
    Ågren, Hans
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology. Siberian Federal University, Russian Federation.
    Grazulevicius, Juozas Vidas
    Contribution of TADF and exciplex emission for efficient "warm-white" OLEDs2018In: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 6, no 6, p. 1543-1550Article in journal (Refereed)
    Abstract [en]

    The bicarbazole derivative 4,4'-(9H, 9'H-[3,3'-bicarbazole]-9,9'-diyl) bis(3-(trifluoromethyl) benzonitrile), denoted as pCNBCzoCF(3), was synthesized and tested for white OLED applications. pCNBCzoCF3 demonstrated an extremely small value of the singlet-triplet energy gap that caused intensive thermally activated delayed fluorescence (TADF). In addition, this compound is able to form exciplex-type excited states at the interface with star-shaped 4,40,400-tris[phenyl(m-tolyl) amino] triphenylamine (m-MTDATA). Combining the TADF emission of pCNBCzoCF3 with the exciplex emission from the pCNBCzoCF(3) m-MTDATA interface, we fabricated a number of highly efficient "warm-white'' OLEDs, the electroluminescence of which was close to candle emission. The best device demonstrated a very high brightness of 40 900 Cd m(-2) (at 15 V), current efficiency of 53.8 Cd A(-1) and power efficiency of 19.3 lm W-1, while the external quantum efficiency reached 18.8%. The fabricated devices demonstrated high emission characteristics even for the standard test at 1000 Cd m(-2) (current efficiency of 46.2 Cd A(-1), power efficiency of 10.6 lm W-1, EQE of 17.0%).

  • 93.
    Gustafsson, Emil
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Tailoring adhesion and wetting properties of cellulose fibers and model surfaces2012Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    The layer-by-layer (LbL) technique was used to modify the surface of cellulose fibers by consecutive adsorption of poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA) followed by a final adsorbed layer of anionic paraffin wax colloids. Paper hand sheets made from the modified fibers were found to be highly hydrophobic with a contact angle of 150°. In addition to the significantly increased hydrophobicity, the sheets showed improved mechanical properties, such as a higher tensile strength. Heat treatment of the prepared sheets further enhanced both the mechanical properties and the hydrophobicity. These results demonstrate the flexibility and robustness of the LbL technique, which allows us to combine the known adhesive effect of PAH/PAA LbL films with the functionality of wax nanoparticles, creating a stronger and highly hydrophobic paper.

    It was further observed that LbL modified sheets without wax also displayed increased hydrophobicity when heat treated. The mechanism was studied through model experiments where LbL films of PAH/PAA were assembled on flat non-porous model cellulose surfaces. Contact angle measurements showed the same trend due to heat treatment of the model films, although, the absolute value of the contact angles were smaller. Analysis using the highly interfacial sensitive vibrational sum frequency spectroscopy technique showed an enrichment of CH3 groups (from the polymer chain ends) at the solid/air interface. These results indicate that during the heat treatment, a reorientation of polymer chains occurs to minimize the surface energy of the LbL film.

    In the second part of this work, the adhesive interactions between the main constituents of wood fibers were studied using high-resolution measuring techniques and well-defined model films of cellulose, hemicellulose and lignin. Successful surface modification of polydimethylsiloxane (PDMS) caps, needed in the Johnson-Kendall-Roberts (JKR) measuring methodology, by LbL deposition of nanofibrillated cellulose (NFC) and poly(ethylene imine) (PEI) allowed for the first known all-wood biopolymer JKR measurements of the adhesion between cellulose/cellulose, cellulose/lignin and the cellulose/glucomannan surfaces. The work of adhesion on loading and the adhesion hysteresis were similar for all three systems, suggesting that adhesion between the different wood biopolymers does not differ greatly.

  • 94.
    Gustafsson, Emil
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Tailoring Adhesion and Wetting Properties of Cellulose Fibres and Model Surfaces Using Layer-by-Layer Technology2014Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The versatile layer-by-layer (LbL) technique, for consecutive adsorption of polyelectrolytes and charged nanoparticles onto a substrate, was used to modify cellulose fibres and model surfaces for improved mechanical and wetting properties. In addition to being used to modify cellulose substrates, the LbL technique was also used to create cellulose surfaces suitable for high resolution adhesion measurements. LbL assembly of cellulose nanofibrils and polyethylenimine was used to prepare cellulose model surfaces on polydimethylsiloxane hemispheres which allowed for the first known Johnson-Kendall-Roberts (JKR) adhesion measurements between cellulose and smooth, well-defined model surfaces of cellulose, lignin and glucomannan. The work of adhesion on loading and the adhesion hysteresis were comparable for all three systems which suggest that adhesion between wood constituents is similar. The LbL technique was also used to decrease the hydrophilicity of paper, while improving the dry strength, by coating cellulose fibres with a polylallylamine hydrochloride (PAH) and polyacrylic acid (PAA) LbL film, followed by adsorption of anionic wax particles. Paper sheets made from the modified fibres were highly hydrophobic with a contact angle of 150°, while retaining, and in some cases improving, the tensile index of the paper. It was also observed that PAH/PAA modified sheets without the addition of wax became hydrophobic when heat treated. The mechanism behind the increased hydrophobicity was studied by the interface sensitive technique, vibrational sum frequency spectroscopy, which indicated that the increased hydrophobicity is a result of the reorientation of polymer chains to expose more hydrophobic CH2 and CH groups at the polymer-air interface. Paper sheets prepared from LbL-modified bleached softwood fibres using PAH and the biopolymer hyaluronic acid (HA) exhibited a 6.5% strain at break and a tensile index which was increased 3-fold compared to unmodified fibres. The wet adhesive properties of the PAH/HA system were studied by colloidal probe atomic force microscopy and correlated to film growth and viscoelastic behavior. The presence of background salt was a crucial parameter for achieving high adhesion but time in contact and LbL film thickness also strongly affected the adhesion. Finally, the wet adhesive properties of carboxymethylcellulose (CMC), which had been irreversibly adsorbed to regenerated cellulose, and polyvinylamine (PVAm) were evaluated by means of 90° peel tests. Strong wet adhesion was achieved for dried rewetted samples without any obvious chemical crosslinking, which was attributed to interdigitation and complex formation in PVAm-CMC films. This system also gave significant wet adhesion for non-dried systems at water contents around 45%.

  • 95.
    Gustafsson, Emil
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Hedberg, Jonas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Larsson, Per A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Johnson, C. Magnus
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Vibrational sum frequency spectroscopy on polyelectrolyte multilayers – effect of molecular surface structure on macroscopic wetting propertiesManuscript (preprint) (Other academic)
  • 96.
    Gustafsson, Emil
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Hedberg, Jonas
    Larsson, Per A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Fibre Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
    Johnson, C. Magnus
    Vibrational sum frequency spectroscopy on polyelectrolyte multilayers: modelling of hydrophobic fibresManuscript (preprint) (Other academic)
  • 97.
    Gustafsson, Stefan
    et al.
    Department of Applied Physics, Chalmers University of Technology.
    Fornara, Andrea
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Petersson, Karolina
    Imego AB.
    Johansson, Christer
    Imego AB.
    Muhammed, Mamoun
    KTH, School of Information and Communication Technology (ICT), Material Physics, Functional Materials, FNM.
    Olsson, Eva
    Department of Applied Physics, Chalmers University of Technology.
    Evolution of Structural and Magnetic Properties of Magnetite Nanoparticles for Biomedical Applications2010In: Crystal Growth & Design, ISSN 1528-7483, E-ISSN 1528-7505, Vol. 10, no 5, p. 2278-2284Article in journal (Refereed)
    Abstract [en]

    We have investigated the evolution of microstructure and magnetic properties of thermally blocked magnetite nanoparticles, aimed for immunoassay applications, during their synthesis. High-resolution transmission electron microscopy (HRTEM) investigations of the size, size distribution, morphology, and crystal structure of particles reveal that particles at an early stage of the reaction process are either single crystals or polycrystals containing planar faults and they grow via a combination of reactant (monomer) consumption and oriented attachment at specific crystallographic surfaces because of the strong dipolar character of the < 111 > surfaces of magnetite. At a later stage of the synthesis reaction, the magnetic attraction strives to align contacting particles with their < 111 > axis of easy magnetization in parallel and this may also be an active driving force for crystal growth. At latter stages, the crystal growth is dominated by Ostwald ripening leading to smoother crystalline particles with a mean diameter of 16.7 +/- 3.5 nm and a narrow size distribution. The magnetic properties of the particles measured using static and dynamic magnetic fields are consistent with the evolution of particle size and structure and show the transition from superparamagnetic to thermally blocked behavior needed for magnetic relaxation-based immunoassay applications.

  • 98.
    Hajian, Alireza
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH.
    Lindström, Stefan B.
    Linköping University.
    Pettersson, Torbjörn
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH.
    Hamedi, Mahiar M.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH.
    Wågberg, Lars
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH.
    Understanding the Dispersive Action of Nanocellulose for Carbon Nanomaterials2017In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 17, no 3, p. 1439-1447Article in journal (Refereed)
    Abstract [en]

    This work aims at understanding the excellent ability of nanocelluloses to disperse carbon nanomaterials (CNs) in aqueous media to form long-term stable colloidal dispersions without the need for chemical functionalization of the CNs or the use of surfactant. These dispersions are useful for composites with high CN content when seeking water-based, efficient, and green pathways for their preparation. To establish a comprehensive understanding of such dispersion mechanism, colloidal characterization of the dispersions has been combined with surface adhesion measurements using colloidal probe atomic force microscopy (AFM) in aqueous media. AFM results based on model surfaces of graphene and nanocellulose further suggest that there is an association between the nanocellulose and the CN. This association is caused by fluctuations of the counterions on the surface of the nanocellulose inducing dipoles in the sp2carbon lattice surface of the CNs. Furthermore, the charges on the nanocellulose will induce an electrostatic stabilization of the nanocellulose–CN complexes that prevents aggregation. On the basis of this understanding, nanocelluloses with high surface charge density were used to disperse and stabilize carbon nanotubes (CNTs) and reduced graphene oxide particles in water, so that further increases in the dispersion limit of CNTs could be obtained. The dispersion limit reached the value of 75 wt % CNTs and resulted in high electrical conductivity (515 S/cm) and high modulus (14 GPa) of the CNT composite nanopapers.

  • 99.
    Halldin Stenlid, Joakim
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Computational Studies of Chemical Interactions: Molecules, Surfaces and Copper Corrosion2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The chemical bond – a corner stone in science and a prerequisite for life – is the focus of this thesis. Fundamental and applied aspects of chemical bonding are covered including the development of new computational methods for the characterization and rationalization of chemical interactions. The thesis also covers the study of corrosion of copper-based materials. The latter is motivated by the proposed use of copper as encapsulating material for spent nuclear fuel in Sweden.

    In close collaboration with experimental groups, state-of-the-art computational methods were employed for the study of chemistry at the atomic scale. First, oxidation of nanoparticulate copper was examined in anoxic aqueous media in order to better understand the copper-water thermodynamics in relation to the corrosion of copper material under oxygen free conditions. With a similar ambition, the water-cuprite interface was investigated with regards to its chemical composition and reactivity. This was compared to the behavior of methanol and hydrogen sulfide at the cuprite surface.

    An overall ambition during the development of computational methods for the analysis of chemical bonding was to bridge the gap between molecular and materials chemistry. Theory and results are thus presented and applied in both a molecular and a solid-state framework. A new property, the local electron attachment energy, for the characterization of a compound’s local electrophilicity was introduced. Together with the surface electrostatic potential, the new property predicts and rationalizes regioselectivity and trends of molecular reactions, and interactions on metal and oxide nanoparticles and extended surfaces.

    Detailed atomistic understanding of chemical processes is a prerequisite for the efficient development of chemistry. We therefore envisage that the results of this thesis will find widespread use in areas such as heterogeneous catalysis, drug discovery, and nanotechnology.

  • 100.
    Halonen, Helena
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Structural changes during cellulose composite processing2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Two approaches for creating a new all-cellulose composite material have been studied: the biosynthesis of compartmentalised bacterial cellulose fibril aggregates and the compression moulding of commercial chemical wood pulps processed with only water. The objective was to study the structural changes during processing and the complexity of relating the mechanical properties of the final biocomposites to the nanoscale structure was highlighted.

    Solid-state CP/MAS 13C NMR spectroscopy was utilised to determine both the fibril aggregate width and the content of the different crystalline cellulose forms, cellulose I and cellulose II. Using this method, the quantities of hemicellulose present inside the fibre wall and localised at the fibre surfaces could be determined.

    The formation of cellulose fibrils was affected by the addition of hydroxyethylcellulose (HEC) to a culture medium of Acetobacter aceti, and the fibrils were coated with a thin layer of HEC, which resulted in loose bundles of fibril aggregates. The HEC coating, improved the fibril dispersion in the films and prevented fractures, resulting in a biocomposite with remarkable mechanical properties including improved strength (289 MPa), modulus (12.5 GPa) and toughness (6%).

    The effect of press temperature was studied during compression moulding of sulphite dissolving-grade pulps at 45 MPa. A higher press temperature yielded increases in the fibril aggregation, water resistance (measured as the water retention value) and Young’s modulus (12 GPa) in the final biocomposite. The high pressure was important for fibril aggregation, possibly including cellulose-cellulose fusion bonds, i.e., fibril aggregation in the fibre-fibre bond region. The optimal press temperature was found to be 170°C because cellulose undergoes thermal degradation at higher temperatures.

    The effect of hemicellulose was studied by comparing a softwood kraft paper-grade pulp with a softwood sulphite paper and a softwood sulphite dissolving-grade pulp. A significant fibril aggregation of the sulphite pulps suggested that the content and distribution of hemicellulose affected the fibril aggregation. In addition, the hemicellulose structure could influence the ability of the hemicellulose to co-aggregate with cellulose fibrils. Both sulphite pulp biocomposites exhibited Young’s moduli of approximately 12 GPa, whereas that of the kraft pulp was approximately half that value at 6 GPa. This result can be explained by a higher sensitivity to beating in the sulphite pulps.

    The effect of mercerisation, which introduces disordered cellulose, on the softwood sulphite dissolving-grade pulp was also studied under compression moulding at 170°C and 45 MPa. The mechanisms causing an incomplete transformation of cellulose I to II in a 12 wt% NaOH solution were discussed. The lower modulus of cellulose II and/or the higher quantity of disordered cellulose likely account for the decrease in Young’s modulus in the mercerised biocomposites (6.0 versus 3.9 GPa).

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