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  • 51. Cifelli, M.
    et al.
    Domenici, V.
    Kharkov, Boris B.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Dvinskikh, Sergey V.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. St. Petersburg State University, Russian Federation.
    Study of Translational Diffusion Anisotropy of Ionic Smectogens by NMR Diffusometry2015In: Molecular Crystals and Liquid Crystals, ISSN 1542-1406, E-ISSN 1563-5287, Vol. 614, no 1, p. 30-38Article in journal (Refereed)
    Abstract [en]

    Thermotropic ionic liquid crystals are considered very promising for a wide range of applications, such as anisotropic conductors as well as electrolytes in dye-synthesized solar cells. Their potential comes from the unique combination of ionic conductivity and high polarizability. In this paper we present a study of the diffusional properties of the ionic smectic A phase formed by the cationic smectogen, N-docecyl-N'-methyl-imidazolium (C12mim), with two different counter ions. Experimental translational diffusion data measured by NMR diffusometry are collected both for cations and anions and discussed in terms of their different anisotropy.

  • 52. Cifelli, Mario
    et al.
    Domenici, Valentina
    Dvinskikh, Sergey V.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Veracini, Carlo Alberto
    Zimmermann, Herbert
    Translational self-diffusion in the smectic phases of ferroelectric liquid crystals: an overview2012In: Phase Transitions, ISSN 0141-1594, E-ISSN 1029-0338, Vol. 85, no 10, p. 861-871Article in journal (Refereed)
    Abstract [en]

    In this work, we present our recent results obtained in the field of translational self-diffusion studies by means of H-1 NMR diffusometry in smectic phases formed by calamitic chiral liquid crystals. In particular, the diffusional behavior of chiral smectic phases with different clinicity, such as the ferroelectric and antiferroelectric phases, will be discussed on the basis of the results obtained on three different chiral smectogens. This research demonstrates that, despite previous assertions, out-of-plane translational diffusion in smectic phases is poorly affected by the clinicity of the phases, showing no discontinuity at the transition from synclinic to anticlinic structures, typical of the smectic C* phases. We can conclude that diffusion basically reflects the layered smectic structure where in-plane diffusion is much faster and less hindered than the out-of-plane one.

  • 53.
    Claudino, Mauro
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Johansson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Thiol-ene coupling kinetics of D-limonene: a versatile 'non-click' free-radical reaction involving a natural terpene2013In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 3, no 27, p. 11021-11034Article in journal (Refereed)
    Abstract [en]

    The free-radical photoinduced thiol-ene reaction between D-limonene, as renewable diolefinic substrate, and two mono-/tri-functional thiols (iso-tridecyl 3-mercaptopropionate and trimethylolpropane tris(3-mercaptopropionate)), has been investigated kinetically to define a relationship between alkene structure and reactivity. Separate thiol-ene solutions of the appropriate thiol in d-chloroform, supplemented with 1.0 wt% of DMPA (Irgacure 651), were subjected to polychromatic UV-irradiation and the chemical changes monitored discontinuously via H-1 NMR spectroscopy to quantify double bond conversion. The kinetic concentration profiles were modeled analytically and simulated in the application software COPASI for parameter estimation and to verify if the experimental data explained a suggested mechanistic scheme. Empirical results demonstrate that the external vinylidene bond of limonene reacts about 6.5 times faster with thiol than the internal trisubstituted 1-methyl-cyclohexene unsaturation. The selectivity observed for the two unsaturations was successfully explained by means of a simplified steady-state equation derived from the sequential reaction mechanism accounting for propagation and chain-transfer elementary steps with estimated rate coefficients. Kinetic modeling results attribute the difference in selectivity partially to steric impediments controlling thiyl-radical insertion onto the double bonds and predominantly to differences in relative energy between the two tertiary insertion carbon radical intermediates. The rate-limiting step was identified as the third chain-transfer hydrogen-abstraction reaction promoted by the second insertion carbon radical intermediate. High thiol-ene conversions were obtained in a timely fashion without major influence of secondary reactions demonstrating the suitability of this reaction for network forming purposes. The mechanistic and kinetic information collected can be used as a quantitative predictive tool to assess the potential use of D-limonene in thiol-ene network forming systems involving multifunctional alkyl ester 3-mercaptopropionates.

  • 54.
    Claudino, Mauro
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Johansson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Utilizing Thiol-Ene Coupling Kinetics in the Design of Renewable Thermosed Resins based on D-Limonene and Polyfunctional ThiolsManuscript (preprint) (Other academic)
  • 55.
    Claudino, Mauro
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Johansson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Utilizing thiol-ene coupling kinetics in the design of renewable thermoset resins based on D-limonene and polyfunctional thiols2014In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 4, no 20, p. 10317-10329Article in journal (Refereed)
    Abstract [en]

    An extended model is developed to predict the free-radical thiol-ene reaction dynamics between D-limonene, as a renewable diolefin, and a monothiol compound (iso-tridecyl 3-mercaptopropionate) in bulk liquid conditions. Thermally and photo-initiated reactions of the two monomers showed favored thiol-ene coupling at the exo-isopropenyl alkene structure when reacted at 1 : 1 and 1 : 0.5 mole ratios. Experimental kinetic data obtained from the two stoichiometries were well reproduced numerically via the simulation software COPASI by introducing a multi-route mechanistic scheme with propagation-chain-transfer steps accounting for primary (mono-additions) and secondary (di-addition) modes of coupling. The differences in intrinsic double-bond reactivity enable synthesis of limonene-terminated resins (mono-versus poly-disperse) as multifunctional network precursors. Off-stoichiometry manipulations in the initial mole ratio, assisted by numerical simulations, offer a convenient approach to visualize the overall reaction system kinetics irrespective of temporal effects, thus being regarded as an important guiding tool for chemists aiming at designing thiol-ene systems based on limonene.

  • 56.
    Claudino, Mauro
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Mathevet, Jeanne-Marie
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Johansson, Mats K. G.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Bringing D-limonene to the scene of bio-based thermoset coatings via free-radical thiol-ene chemistry: macromonomer synthesis, UV-curing and thermo-mechanical characterization2014In: Polymer Chemistry, ISSN 1759-9954, Vol. 5, no 9, p. 3245-3260Article in journal (Refereed)
    Abstract [en]

    The increasing pursuit for bio-based plastic materials led us to investigate the potential use of the monoterpene limonene in thermoset synthesis using the free-radical mediated thiol-ene reaction. The high efficiency of this reaction to prepare multifunctional ene-terminated resins, as intermediary macromolecular precursors, for thermosets synthesis was demonstrated under thermal and photoinitiated conditions. Although an excess of terpene favors formation of well-defined macromonomers in organic solution, the characteristic low-vapor pressure of limonene hinders its simple removal (or recycling) via evaporation after synthesis. Alteration to an initial thiol-ene stoichiometry of 1 : 0.5 enables production of high molecular weight resins in the form of 'hyperbranched oligomeric-like' structures having moderate polydispersity. UV-curing of these polyfunctional resins combined with equal mole compositions of multifunctional alkyl ester 3-mercapto propionates yields highly sticky, amorphous and flexible elastomers with different thermo-mechanical properties. These can be further modulated by varying the amount of unreacted thiol occluded within the networks working as a plasticizer. Introduction of a renewable cycloaliphatic structure into the materials offers a convenient way to enhance the glass-transition temperature and stiffness of traditional thiol-ene networks. The materials synthesized may be considered potentially useful as sealants and adhesives in a wide variety of applications including organic coatings. The versatility of UV-irradiation over thermal initiation makes this method particularly suitable for green industrial synthesis processes via thiol-ene chemistry using limonene and multifunctional thiols. The thiol-ene system evaluated herein serves as a model example for the sustainable incorporation of natural diolefinic monomers into semisynthetic thiol-ene networks exhibiting a range of thermo-mechanical properties.

  • 57.
    Cong, Jiayan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hao, Yan
    Boschloo, Gerrit
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Electrolytes Based on TEMPO-Co Tandem Redox Systems Outperform Single Redox Systems in Dye-sensitized Solar Cells2015In: ChemSusChem, ISSN 1864-5631, E-ISSN 1864-564X, Vol. 8, no 2, p. 264-268Article in journal (Refereed)
    Abstract [en]

    A new TEMPO-Co tandem redox system with TEMPO and Co(bpy)(3)(2+/3+) has been investigated for the use in dye-sensitized solar cells (DSSCs). A large open-circuit voltage (V-OC) increase, from 862 mV to 965 mV, was observed in the tandem redox system, while the short-circuit current density (J(SC)) was maintained. The conversion efficiency was observed to increase from 7.1% for cells containing the single Co(bpy)(3)(2+/3+) redox couple, to 8.4% for cells containing the TEMPO-Co tandem redox system. The reason for the increase in V-OC and overall efficiency is ascribed to the involvement of partial regeneration of the sensitizing dye molecules by TEMPO. This assumption can be verified through the observed much faster regeneration dynamics exhibited in the presence of the tandem system. Using the tandem redox system, the faster recombination problem of the single TEMPO redox couple is resolved and the mass-transport of the metal-complex-based electrolyte is also improved. This TEMPO-Co tandem system is so far the most effienct tandem redox electrolyte reported not involving iodine. The current results show a promising future for tandem system as replacements for single redox systems in electrolytes for DSSCs.

  • 58.
    Cong, Jiayan
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Hao, Yan
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Two Redox Couples are Better Than One: Improved Current and Fill Factor from Cobalt-Based Electrolytes in Dye-Sensitized Solar Cells2014In: Advanced Energy Materials, ISSN 1614-6832, Vol. 4, no 8, p. 1301273-Article in journal (Refereed)
    Abstract [en]

    A tandem redox strategy is used in cobalt-based electrolytes. Co(bpy) 3 2+/Co(bpy)3 3+ offers a high photovoltage at the photoanode, whereas the I-/I3 - or Fc/Fc+ redox couples facilitate charge transfer at the counter electrode. Electron exchange in the electrolyte offers beneficial concentration gradients. The overall conversion efficiency is improved from 6.5% to 7.5%.

  • 59.
    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.

  • 60. Cong, Jiayan
    et al.
    Yang, Xichuan
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry. KTH, School of Chemical Science and Engineering (CHE), Centres, Centre of Molecular Devices, CMD.
    Iodine/iodide-free redox shuttles for liquid electrolyte-based dye-sensitized solar cells2012In: Energy & Environmental Science, ISSN 1754-5692, E-ISSN 1754-5706, Vol. 5, no 11, p. 9180-9194Article, review/survey (Refereed)
    Abstract [en]

    Dye-sensitized solar cells have attracted intense academic interest over the past two decades. For a long time, the development of new redox systems has fallen far behind that of the sensitizing dyes and other materials. However, the field has received renewed attention recently. In particular, in 2011, the Gratzel group published a record DSC efficiency of 12.3% by using a new Co-complex-based electrolyte. In this review, we will provide an overview of iodine/iodide-free redox systems for liquid electrolytes, and reveal that the design of an efficient redox system should combine with appropriate sensitizing dyes which is the pivotal challenge for highly efficient DSCs.

  • 61.
    Corkery, Robert W.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. The Australian National University, Australia.
    Tyrode, Eric C.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    On the colour of wing scales in butterflies: Iridescence and preferred orientation of single gyroid photonic crystals2017In: Interface Focus, ISSN 2042-8898, E-ISSN 2042-8901, Vol. 7, no 4Article in journal (Refereed)
    Abstract [en]

    Lycaenid butterflies from the genera Callophrys, Cyanophrys and Thecla have evolved remarkable biophotonic gyroid nanostructures within their wing scales that have only recently been replicated by nanoscale additive manufacturing. These nanostructures selectively reflect parts of the visible spectrum to give their characteristic non-iridescent, matte-green appearance, despite a distinct blue-green-yellow iridescence predicted for individual crystals from theory. It has been hypothesized that the organism must achieve its uniform appearance by growing crystals with some restrictions on the possible distribution of orientations, yet preferential orientation observed in Callophrys rubi confirms that this distribution need not be uniform. By analysing scanning electron microscope and optical images of 912 crystals in three wing scales, we find no preference for their rotational alignment in the plane of the scales. However, crystal orientation normal to the scale was highly correlated to their colour at low (conical) angles of view and illumination. This correlation enabled the use of optical images, each containing up to 104-105 crystals, for concluding the preferential alignment seen along the k100l at the level of single scales, appears ubiquitous. By contrast, k110l orientations were found to occur at no greater rate than that expected by chance. Above a critical cone angle, all crystals reflected bright green light indicating the dominant light scattering is due to the predicted band gap along the k110l direction, independent of the domain orientation. Together with the natural variation in scale and wing shapes, we can readily understand the detailed mechanism of uniform colour production and iridescence suppression in these butterflies. It appears that the combination of preferential alignment normal to the wing scale, and uniform distribution within the plane is a near optimal solution for homogenizing the angular distribution of the k110l band gap relative to the wings. Finally, the distributions of orientations, shapes, sizes and degree of order of crystals within single scales provide useful insights for understanding the mechanisms at play in the formation of these biophotonic nanostructures.

  • 62. Crespi, Miguel Coll
    et al.
    Crespo, Gaston A.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Xie, Xiaojiang
    Touilloux, Romain
    Tercier-Waeber, Marylou
    Bakker, Eric
    Agarose hydrogel containing immobilized pH buffer microemulsion without increasing permselectivity2018In: Talanta: The International Journal of Pure and Applied Analytical Chemistry, ISSN 0039-9140, E-ISSN 1873-3573, Vol. 177, p. 191-196Article in journal (Refereed)
    Abstract [en]

    A heterogeneous pH buffer based on a colloidal emulsion containing ion-exchanger and lipophilic base is described that can be integrated into hydrogels without affecting their ion-exchange properties. Each sphere works on the basis of reversible ion-exchange of hydrogen ions with solution cations, acting as a pH buffer while staying removed from solution in the nonpolar core of the spheres. The ion-exchange mechanism is supported by titration experiments in aqueous emulsion, showing that the nature and concentration of the exchanging solution cations influences the buffer action, with increasing lipophilicity moving the equilibrium to lower pH values. Agarose gels with entrapped pH buffer emulsions and mounted in a transport cell are shown by zero current potentiometry to exhibit negligible permselective properties above an ionic strength of 1 mM, a behavior no different from unmodified agarose, with an observed ion-exchanger concentration of 7 mM in dry agarose. This suggests that such pH buffers do not give rise to substantial ion-exchange properties of the gel material. In a first attempt to control the pH in the vicinity of an electrode surface by this approach, the emulsion was entrapped in an agarose gel in direct contact with a pH electrode, demonstrating the ability to buffer such gel films.

  • 63.
    Crespo, Gaston A.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Recent Advances in Ion-selective membrane electrodes for in situ environmental water analysis2017In: Electrochimica Acta, ISSN 0013-4686, E-ISSN 1873-3859, Vol. 245, p. 1023-1034Article, review/survey (Refereed)
    Abstract [en]

    Ion-selective membrane electrodes (ISEs) have become very attractive sensing platforms for environmental water analysis. This review mainly presents recent advances in polymeric-based ISEs relevant to water research and primarily focused on alkali and alkali earth-metal cations, ammonium ions, halide anions and certain oxoanions involved in biogeochemical cycles (e.g. nutrients (NO2 −, NO3 −), carbon (HCO3 −/CO3 2−) and phosphorus (HPO4 2−/H2PO4 −)). Clearly, ISEs have the potential to be the icon of decentralized ion chemical information for water research as in the case of wearable ISE sensors. The modern development of robust ISEs (mainly in all-solid-state format) has allowed an easy implementation either into submersible or non-submersible probes that maintain, to an acceptable degree, the required analytical performance. Remarkable benefits, such as avoidance of sample contamination, sample preservation and determination of perturbations of chemical speciation, are significant to enhancing the fundamental knowledge of ongoing biogeochemical process. A perspective on the current requirements of ISEs in terms of analytical performance and engineering construction is provided initially and is followed by recent contributions listed according to the sampling methodology, including i) on-board/on-site sampling with subsequent coverage of decentralized analysis (on moving or fixed platforms) and ii) in situ monitoring with submersible sensing probes. On the one hand, there is difficulty in making a general statement about ISEs for water research, specifically in terms of whether they are suitable. This lies in the complexity and heterogeneity of the samples. Accordingly, particular scenarios are discussed. On the other hand, it is also evident that further steps are still needed at the fundamental level, including development of receptors, robust membranes and novel alternatives that would enable the sensing of ions at deep-sea. Importantly, there is a plenty of room for improvement and new approaches; and it should be stressed that the recent progress in water research using ISEs has been owing to multidisciplinary efforts. Facing this challenge is very exciting and the development of ISE platforms that enable working in real conditions is quite plausible.

  • 64.
    Cuartero, Maria
    et al.
    Univ Geneva, Dept Inorgan & Analyt Chem, Quai Ernest Ansermet 30, CH-1211 Geneva, Switzerland..
    Acres, Robert G.
    ANSTO, Australian Synchrotron, 800 Blackburn Rd, Clayton, Vic 3168, Australia..
    Jarolimova, Zdenka
    Univ Geneva, Dept Inorgan & Analyt Chem, Quai Ernest Ansermet 30, CH-1211 Geneva, Switzerland..
    Bakker, Eric
    Univ Geneva, Dept Inorgan & Analyt Chem, Quai Ernest Ansermet 30, CH-1211 Geneva, Switzerland..
    Crespo, Gaston A.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. Univ Geneva, Dept Inorgan & Analyt Chem, Quai Ernest Ansermet 30, CH-1211 Geneva, Switzerland.
    De Marco, Roland
    Univ Sunshine Coast, Fac Sci Hlth Educ & Engn, 90 Sippy Downs Dr, Sippy Downs, Qld 4556, Australia.;Univ Queensland, Sch Chem & Mol Biosci, Brisbane, Qld 4072, Australia.;Curtin Univ, Dept Chem, GPO Box U1987, Perth, WA 6109, Australia..
    Electron Hopping between Fe 3d States in Ethynylferrocene-doped Poly(Methyl Methacrylate)-poly(Decyl Methacrylate) Copolymer Membranes2018In: Electroanalysis, ISSN 1040-0397, E-ISSN 1521-4109, Vol. 30, no 4, p. 596-601Article in journal (Refereed)
    Abstract [en]

    Synchrotron radiation-valence band spectroscopy (SR-VBS) has been utilized in a study of redox molecule valence states implicated in the electron hopping mechanism of ethynylferrocene in unplasticized poly(methyl methacrylate)-poly(decyl methacrylate) [PMMA-PDMA] membranes. In this communication, it is revealed that, at high concentrations of ethynylferrocene, there are observable Fe 3d valence states that are likely linked to electron hopping between ferrocene moieties of neighbouring redox molecules. Furthermore, electrochemically induced stratification of ethynylferrocene in an oxidized PMMA-PDMA membrane produces a gradient of Fe 3d states toward the buried interface at the glassy carbon/PMMA-PDMA membrane enabling electron hopping and electrochemical reactivity of dissolved ethynylferrocene across this buried film.

  • 65. Cuartero, Maria
    et al.
    Pankratova, Nadezda
    Cherubini, Thomas
    Crespo, Gaston A.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Massa, Francesco
    Confalonieri, Fabio
    Bakker, Eric
    In Situ Detection of Species Relevant to the Carbon Cycle in Seawater with Submersible Potentiometric Probes2017In: ENVIRONMENTAL SCIENCE & TECHNOLOGY LETTERS, ISSN 2328-8930, Vol. 4, no 10, p. 410-415Article in journal (Refereed)
    Abstract [en]

    We report on the development of a submersible probe for the simultaneous potentiometric detection of carbonate, calcium, and pH in seawater. All-solid-state electrodes incorporating nanomaterials provide an adequate response time (<10 s), stability (drifts of <0.9 mV h(-1)), reproducibility (calibration parameter deviation of <0.7%), and accuracy (deviation of <8% compared to reference techniques) for real-time monitoring of seawater using a flow system. The functioning of the deployable prototype was checked in an outdoor mesocosm and via long-term monitoring in Genoa Harbor. The electrodes worked properly for 3 weeks, and the system demonstrated the capability to autonomously operate with routines for repetitive measurements, data storage, and management. In situ profiles observed in Genoa Harbor and Arcachon Bay were validated using on site and ex situ techniques. The validation of in situ-detected carbonate is a challenge because both re-equilibration of the sample with atmospheric CO2 and the use of apparent thermodynamic constants for speciation calculations lead to some differences (<20% deviation). The submersible probe is a promising tool for obtaining rapid and trustworthy information about chemical levels in marine systems. Moreover, the fluidic approach allows for the integration of other ion sensors that may require sample pretreatment.

  • 66.
    Dai, Jing
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Adsorption, aggregation and phase separation in colloidal systems2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The thesis presents work regarding amphiphilic molecules associated in aqueous solution or at the liquid/solid interface. Two main topics are included: the temperature-dependent behavior of micelles and the adsorption of dispersants on carbon nanotube (CNT) surfaces. Various NMR methods were used to analyze those systems, such as chemical shift detection, spectral intensity measurements, spin relaxation and, in particular, self-diffusion experiments. Besides this, small angle X-ray scattering (SAXS) was also applied for structural characterization.

     

    A particular form of phase transition, core freezing, was detected as a function of temperature in micelles composed by a single sort of Brij-type surfactants. In mixed micelles, that phase transition still occurs accompanied by a reversible segregation of different surfactants into distinct aggregates. Adding a hydrophobic solubilizate shifts the core freezing point to a lower temperature. Upon lowering the temperature to the core freezing point, the solubilizate is released. The temperature course of the release curves with different initial solubilizate loadings is rationalized in terms of a temperature-dependent loading capacity.

     

    The behavior of amphiphilic dispersant molecules in aqueous dispersions of carbon nanotubes (CNTs) has been investigated with a Pluronic-type block copolymer as frequent model dispersant. Detailed dispersion curves were recorded and the distribution of the dispersant among different available environments was analyzed. The amount of dispersed CNT was shown to be defined by a complex interplay of several factors during the dispersion process such as dispersant concentration, sonication time, centrifugation and CNT loading. In the dispersion process, high amphiphilic concentration is required because the pristine CNT surfaces made available by sonication must be rapidly covered by dispersants to avoid their re-attachment. In the prepared dispersions, the competitive adsorption of possible dispersants was investigated that provided information about the relative strength of the interaction of those with the nanotube surfaces. Anionic surfactants were found to have a strong tendency to replace Pluronics, which indicates a strong binding of those surfactants.

     

    CNTs were dispersed in an epoxy resin to prepare nanotube-polymer composites. The molecular mobility of epoxy was investigated and the results demonstrated the presence of loosely associated CNT aggregates within which the molecular transport of epoxy is slow because of strong attractive intermolecular interactions between epoxy and the CNT surface. The rheological behavior is dominated by aggregate-aggregate jamming.

  • 67.
    Dai, Jing
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Alaei, Zahra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Plazzotta, Beatrice
    Pedersen, Jan Skov
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Release of Solubilizate from Micelle upon Core Freezing2017In: Journal of Physical Chemistry B, ISSN 1520-6106, E-ISSN 1520-5207, Vol. 121, no 45, p. 10353-10363Article in journal (Refereed)
    Abstract [en]

    By combining NMR (yielding H-1 chemical shift, spin relaxation, and self-diffusion data) and small-angle X-ray scattering experiments, we investigate the complex temperature dependence of the molecular and aggregate states in aqueous solutions of the surfactant [CH3(CH2)(17)(OCH2CH2)(20)OH], abbreviated as C18E20, and.hexamethyldisiloxane, HMDSO. The latter molecule serves as a model for hydrophobic solubilizates. Previously, the pure micellar solution was demonstrated to exhibit core freezing at approximately 7-8 degrees C. At room temperature, we find that HMDSO solubilizes at a volume fraction of approximately 10% in the core of the C18E20 micelles, which consists of molten and thereby highly mobile alkyl chains. Upon lowering the temperature, core freezing is found, just like in pure micelles, but at a temperature shifted significantly to 3 degrees C. The frozen cores contain immobile alkyl chains and exhibit a higher density but are essentially devoid (volume fraction below 1%) of the solubilizate. The latter molecules are released, first gradually and then rather steeply, from the core in the temperature range that is roughly delimited by the two core freezing temperatures, one for pure micelles and one for micelles with solubilizates. The release behavior of systems with different initial HMDSO loading follows the same master curve. This feature is rationalized in terms of loading capacity being strongly temperature dependent: upon lowering the temperature, release commences once the loading capacity descends below the actual solubilizate content. The sharp release curves and the actual release mechanism with its molecular features shown in rich detail have some bearing on a diverse class of possible applications.

  • 68.
    Dai, Jing
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Ferreira Fernandes, Ricardo Manuel
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Regev, Oren
    Marques, Eduardo
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    The dispersion process of carbon nanotubes sonicated in aqueous solutions of a dispersantManuscript (preprint) (Other academic)
    Abstract [en]

    Single-walled carbon nanotube (SWNT) dispersions are created by sonicating pristine SWNT powders added to aqueous solutions of the dispersant block copolymer Pluronic F127. In those dispersions, the amount of the dispersed SWNT is determined by the combination of TGA and UV-Vis methods, while the dispersant concentration is estimated by 1H NMR spectroscopy. In addition, the amount of dispersant adsorbed at the SWNT surface is obtained by 1H NMR diffusion experiments. A part of the dispersant is taken up by non-dispersed and precipitated particles. Dispersion curves recording the amount of the dispersed SWNT as a function of either the initial dispersant concentration or the final dispersant concentration are obtained at different initial SWNT loadings and sonication times. The results show in detail the way the original SWNT particles are divided into smaller and smaller sizes thereby increasing the available SWNT surface to be covered by dispersant. Centrifugation sets the size-threshold above which SWNT particles are retained in the dispersion which determined the SWNT content as a function of sonication time.

  • 69. Desiraju, Gautam R.
    et al.
    Ho, P. Shing
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Legon, Anthony C.
    Marquardt, Roberto
    Metrangolo, Pierangelo
    Politzer, Peter
    Resnati, Giuseppe
    Rissanen, Kari
    Definition of the halogen bond (IUPAC Recommendations 2013)2013In: Pure and Applied Chemistry, ISSN 0033-4545, E-ISSN 1365-3075, Vol. 85, no 8, p. 1711-1713Article in journal (Refereed)
    Abstract [en]

    This recommendation proposes a definition for the term "halogen bond", which designates a specific subset of the inter- and intramolecular interactions involving a halogen atom in a molecular entity.

  • 70.
    Diesen, Veronica
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Heterogeneous TiO2 Photocatalysis: Fundamental Chemical Aspects and Effects of Solid Phase Alterations2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Heterogeneous photocatalysis on TiO2 is an emerging green technology for water disinfection. The rationale for this technology is based on in-situ generation of highly reactive transitory species for degradation of organic and inorganic pollutants as well as microorganisms. Recent research has concentrated on improving the efficiency of the photocatalytic process, however, some fundamental information on the mechanistic aspects and rate limiting properties still remain elusive. 

       The focus of this thesis has been to identify the primary oxidant in heterogeneous TiO2 photocatalysis and to create prerequisites for further evaluation of how selected internal (material specific) and external (system specific) alterations influence the photocatalytic activity. Furthermore, an attempt to induce visible light activity to a modified TiO2 film was also made.

       Production of H2O2 was used to probe the existence of the hydroxyl radical as the primary oxidizing species in aqueous TiO2 photocatalysis. The only possible pathway to produce H2O2 in an oxygen free environment is through hydroxyl radical recombination. A significant amount of H2O2 could be detected in deoxygenated solutions confirming the existence of hydroxyl radicals. To further elucidate the origin of the H2O2, experiments with the hydroxyl radical scavenger Tris(hydroxymethyl)aminomethane (Tris) were performed. The results further support the hypothesis that the hydroxyl radical is the primary oxidant in TiO2 photocatalysis.

       Tris was evaluated as a probe in aqueous photocatalysis. Hydrogen abstracting species such as hydroxyl radicals are able to abstract hydrogen atoms from Tris, which leads to formation of formaldehyde. Formaldehyde was detected and quantified by a modified version of the Hantzsch reaction. This route to probe the photocatalytic efficiency allows for assessment of the maximum photocatalytic efficiency with high accuracy and sensitivity and was further used to study how selected solid phase alterations and dissolved electron acceptors affect the photocatalytic efficiency. The results showed that the surface area of immobilized photocatalysts affects the efficiency and a high surface area is advantageous for photocatalysis. It was also shown that TiO2 enhanced with Ag nanoparticles significantly increases photocatalytic activity. This is explained partly by an increased O2 adsorption and reduction process on the Ag enhanced TiO2 compared to pure TiO2 and partly as a Schottky barrier formation at the metal-semiconductor interface. These processes lead to a prolonged charge separation in the photocatalyst, which is advantageous for the efficiency. Moreover, the effect of the external, dissolved electron acceptors H2O2 and O2 were also evaluated by Tris. The results showed an increased photocatalytic activity upon addition of the electron acceptors. It was also shown that the adsorption affinity of a reactant to the photocatalyst is rate controlling and governs the kinetics.

       An attempt to induce visible light activity into a TiO2 film was also made by a post-treatment in liquid NH3. The slightly narrowed bandgap of the resulting film caused a red-shift in the absorption band and the film showed visible light activity under illumination by white light with a cut-off filter at 385 nm.

  • 71.
    Diesen, Veronica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Dunnill, Charles W.
    Bear, Joseph C.
    Firth, Steve
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Parkin, Ivan Paul
    Visible Light Photocatalytic Activity in AACVD-Prepared N-modified TiO2 Thin Films2014In: Chemical Vapor Deposition, ISSN 0948-1907, E-ISSN 1521-3862, Vol. 20, no 1-3, p. 91-97Article in journal (Refereed)
    Abstract [en]

    Nitrogen-modified TiO2 thin films are obtained, for the first time, from aerosol-assisted (AA)CVD-prepared samples via a post-treatment method involving immersion in liquid ammonia to achieve nitrogen-modified TiO2 and visible-light photo-activity. The resulting modified and unmodified TiO2 films are characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution (HR)TEM, energy dispersive X-ray (EDX) spectroscopy, selected area electron diffraction (SAED), UV-vis spectroscopy, and X-ray photoelectron spectroscopy (XPS). This shows that the films are approximate to 200nm thick and contain anisotropic crystals of anatase TiO2. XPS shows that the nitrogen is successfully added to the surface of the film interstitially at 0.7 at.-%, but is only present to a film depth of 50nm. The nitrogen doping causes a red shift in the absorption band and a band gap narrowing of approximate to 0.1eV. The surface-bound nitrogen results from the post-treatment method of doping where the films are soaked in liquid ammonia before annealing. The photocatalytic efficiencies of the films under visible light (>385nm) are evaluated by measuring formaldehyde formation from the probe molecule tris(hydroxymethyl)aminomethane (Tris). Hydrogen abstraction from Tris, obtained from, e.g., photocatalytically produced OH radicals, leads to formaldehyde formation which is then detected through a modified version of the Hantzsch reaction. The results show that the N-modified film possess remarkable photocatalytic properties with an apparent photochemical quantum yield of approximate to 8%. Nitrogen-modified TiO2 thin films are obtained from aerosol-assisted (AA)CVD-prepared samples via a post-treatment method of immersion in liquid ammonia and calcining at 500 degrees C. The films are characterized and shown to have visible light photocatalytic activity. Visible light photoactivity is shown by measuring formaldehyde formation from the probe molecule tris(hydroxymethyl)aminomethane.

  • 72.
    Diesen, Veronica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Dunnill, Charles W.
    Österberg, Elin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Parkin, Ivan Paul
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Silver enhanced TiO2 thin films: photocatalytic characterization using aqueous solutions of tris(hydroxymethyl)aminomethane2014In: Dalton Transactions, ISSN 1477-9226, E-ISSN 1477-9234, Vol. 43, no 1, p. 344-351Article in journal (Refereed)
    Abstract [en]

    The photocatalytic activity in aqueous solutions of TiO2 and Ag enhanced TiO2 sol-gel produced films was characterized using tris(hydroxymethyl)aminomethane (Tris) under black light (365 nm) and the observed differences in efficiency were further investigated by O-2 adsorption studies using the same probe. Hydrogen abstracting species, such as hydroxyl radicals formed upon photocatalysis, are able to abstract hydrogen from Tris. This reaction leads to the formation of formaldehyde which was detected and quantified through a modified version of the Hantzsch reaction. It was found that the Ag enhanced TiO2 film increased the apparent quantum yield from 7% to 12%, partly as a result of a Schottky barrier formation at the metal-semiconductor interface and partly as the sensitizing effect of Ag nanoparticles extends the visible light absorption, which through electron transfer processes enable an efficient charge separation in the TiO2 by attracting acceptor species more efficiently than pure TiO2. The O-2 adsorption studies in this paper showed that the Ag enhanced TiO2 film has a stronger adsorption affinity than pure TiO2 towards O-2, which make the reduction of O-2 more efficient with a subsequent enhanced electron-hole lifetime. It was also found that the Ag enhanced TiO2 film had a poorer adsorption affinity for Tris than the pure TiO2 film, which is a consequence of fewer available surface adsorption sites due to the Ag coverage at 64% which agrees well with the obtained adsorption equilibrium constants (K-LH(TiO2) = 615 M-1 and KLH(Ag-TiO2) = 320 M-1).

  • 73.
    Diesen, Veronica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Forsberg, Kerstin
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Effects of cellulose degradation products on the mobility of Eu(III) in repositories for low and intermediate level radioactive waste2017In: Journal of Hazardous Materials, ISSN 0304-3894, E-ISSN 1873-3336, Vol. 340, p. 384-389Article in journal (Refereed)
    Abstract [en]

    The deep repository for low and intermediate level radioactive waste SFR in Sweden will contain large amounts of cellulosic waste materials contaminated with radionuclides. Over time the repository will be filled with water and alkaline conditions will prevail. In the present study degradation of cellulosic materials and the ability of cellulosic degradation products to solubilize and thereby mobilise Eu(III) under repository conditions has been investigated. Further, the possible immobilization of Eu(III) by sorption onto cement in the presence of degradation products has been investigated. The cellulosic material has been degraded under anaerobic and aerobic conditions in alkaline media (pH: 12.5) at ambient temperature. The degradation was followed by measuring the total organic carbon (TOC) content in the aqueous phase as a function of time. After 173 days of degradation the TOC content is highest in the anaerobic artificial cement pore water (1547 mg/L). The degradation products are capable of solubilising Eu(III) and the total europium concentration in the aqueous phase was 900 μmol/L after 498 h contact time under anaerobic conditions. Further it is shown that Eu(III) is adsorbed to the hydrated cement to a low extent (<9 μmol Eu/g of cement) in the presence of degradation products.

  • 74.
    Diesen, Veronica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Comment on the Use of Phenols as Probes for the Kinetics of Heterogeneous PhotocatalysisManuscript (preprint) (Other academic)
  • 75.
    Diesen, Veronica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Comment on the use of phenols as probes for the kinetics of heterogeneous photocatalysis2014In: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 158, p. 429-431Article in journal (Refereed)
  • 76.
    Diesen, Veronica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Effects of O2 and H2O2 on TiO2 photocatalytic efficiency quantified by formaldehyde formation from tris(hydroxymethyl)aminomethane2013In: Journal of AOTS. Advanced Oxidation Technologies, ISSN 1203-8407, Vol. 16, no 1, p. 16-22Article in journal (Refereed)
    Abstract [en]

    The impact of O2 and H2O2 on the efficiency of TiO2 photocatalysis has been studied in this work. Tris(hydroxymethyl)aminomethane (Tris) was used to probe the efficiency. Upon hydrogen abstraction by e.g. hydroxyl radicals from Tris, formaldehyde is formed. This product was detected and quantified using a modified version of the Hantzsch method. A significant increase in the formaldehyde production rate was observed upon addition of O2 or H2O2. It was also found that O2 and H2O2 are equally effective in scavenging the photo-excited electron, which is probably a result of their similar adsorption properties. A strong concentration dependence, independent of O2 or H2O2 content, was found at low Tris concentrations (&lt;100 mM). Adsorption studies of H2O 2 onto the TiO2 surface were performed in order to explore the rate controlling reactions. The results show that H2O 2, having a stronger adsorption affinity than Tris towards the photocatalytic surface, govern the kinetics, but only until a monolayer is built up.

  • 77.
    Diesen, Veronica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Formation of H2O2 in TiO2 Photocatalysis of Oxygenated and Deoxygenated Aqueous Systems: A Probe for Photocatalytically Produced Hydroxyl Radicals2014In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 118, no 19, p. 10083-10087Article in journal (Refereed)
    Abstract [en]

    The formation of H2O2 in oxygenated and deoxygenated aqueous solutions using immobilized TiO2 illuminated by black light (365 nm) was studied to verify the presence of hydroxyl radicals in TiO2 photocatalysis. In oxygen containing systems, formation of H2O2 proceeds through reduction of molecular oxygen by conduction band electrons or by recombination of hydroxyl radicals. In oxygen free solutions recombination of hydroxyl radicals constitutes the only pathway to H2O2 formation. Detection of H2O2 in absence of oxygen therefore serves as an indicator for hydroxyl radical formation. The H2O2 concentration was determined using the Ghormley triiodide method. It was found that a significant amount of H2O2 was produced in the deoxygenated aqueous solutions supporting the hypothesis of hydroxyl radical production in photocatalysis. To further elucidate the origin of the H2O2, experiments using the radical scavenger tris(hydroxymethyL)aminomethane (Tris) were conducted. The results showed that the H2O2 concentration increased in the oxygenated system as Tris protects the H2O2 from decomposition by hydroxyl radicals. In the deoxygenated system, no H2O2 could be detected due to hydroxyl radical scavenging by Tris, which prevents H2O2 formation. The results presented support the hypothesis that the hydroxyl radical is the primary oxidant in aqueous TiO2 photocatalysis.

  • 78.
    Diesen, Veronica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Tris(hydroxymethyl)aminomethane as a probe in heterogeneous TiO 2 photocatalysis2012In: Journal of AOTS. Advanced Oxidation Technologies, ISSN 1203-8407, Vol. 15, no 2, p. 392-398Article in journal (Refereed)
    Abstract [en]

    In this work we present a new route to probe the efficiency of aqueous TiO 2 photocatalysis using Tris(hydroxymethyl)aminomethane (Tris). Hydrogen abstracting species such as hydroxyl radicals react with Tris through hydrogen abstraction, which leads to the formation of formaldehyde. Formaldehyde was subsequently detected and quantified spectrophotometrically at 368 nm using a modified version of the Hantzsch reaction. The effect of Tris concentration on the photocatalytic production of formaldehyde was studied in the range 0.1-500 mM Tris. A strong concentration dependence was observed below 100 mM, which indicates that not all photo-produced (hydroxyl) radicals are scavenged at Tris concentrations below 100 mM. Therefore, in order to assess the maximum efficiency of the photocatalytic system, Tris concentrations above 100 mM are required. To evaluate the effect of O 2 on the formaldehyde yield in the reaction between Tris and the hydroxyl radical, a gamma radiolysis study was performed where Tris solutions saturated with O 2 and N 2, respectively, were irradiated in parallel and the yield of formaldehyde was compared. These results showed that O2 does not influence the formaldehyde yield.

  • 79.
    Diesen, Veronica
    et al.
    Materials Chemistry Research Centre, Department of Chemistry University College London.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Parkin, Ivan Paul
    Improved Texturing and Photocatalytic Efficiency in TiO2 Films Grown Using Aerosol-Assisted CVD and Atmospheric Pressure CVD2013In: Chemical Vapor Deposition, ISSN 0948-1907, E-ISSN 1521-3862, Vol. 19, no 10-12, p. 355-362Article in journal (Refereed)
    Abstract [en]

    Four different TiO2 films are formed on glass at 500 degrees C by aerosol-assisted (AA)CVD, atmospheric pressure (AP)CVD, AACVD followed by APCVD, and APCVD followed by AACVD. The APCVD films are formed from reaction of TiCl4(g) whilst the AACVD films are made by decomposing Ti[OCH(CH3)(2)](4) contained in an aerosol. The film composition is studied using X-ray photoelectron spectroscopy (XPS) to ascertain the purity of the films, and no Cl traces can be found on any of the surfaces. The use of different combinations of CVD gives rise to significant changes in microstructure and preferred orientations. X-ray diffraction (XRD) patterns and Raman spectroscopy (RS) confirm that TiO2 in the anatase form is the dominant phase on all samples. All films show superhydrophilicity after 50min of black-light irradiation. The photocatalytic efficiencies of the films are assessed qualitatively by an ink test based on Resazurin, and quantitatively studied by measuring formaldehyde formation from tris(hydroxymethyl)aminomethane (Tris). Both methods show that the AACVD film and the film seeded by APCVD are the most photocatalytically efficient ones, both having an apparent quantum yield (AQY) of around 4.2%, while the APCVD film and the film seeded by AACVD have an AQY of 0.8% and 1.5%, respectively. The changes in photocatalytic activity are explained in part by changes in film microstructure and the accessible surface area.

  • 80.
    Diesen, Veronica
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Lousada, Claudio
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Fischer, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    A hydrogen sulfate salt of chlordiazepoxide2012In: Acta Crystallographica Section E: Structure Reports Online, ISSN 1600-5368, E-ISSN 1600-5368, Vol. 68, no 7, p. o2091-o2092Article in journal (Refereed)
    Abstract [en]

    Crystals of the hydrogen sulfate salt of chlordiazepoxide (systematic name: 7-chloro-Nmethyl-5-phenyl-2,3-dihydro-1H-1,4-benzodiazepin-2-iminium 4-oxide hydrogen sulfate), C 16H 15ClN 3O +·HSO 4 -, were obtained from a solution of chlordiazepoxide and sulfuric acid in methanol. The structure features chlordiazepoxide molecules that are protonated at the imine N atom. The seven-membered ring adopts a boat conformation with the CH 2 group as the prow and the two aryl C atoms as the stern. The dihedral angle between the benzene rings is 72.41 (6)°. In the crystal, the HSO 4 - anion acts as a bridging group between two chlordiazepoxide cations. The H atom of the protonated imino N forms an N - H⋯O hydrogen bond with a hydrogen sulfate ion. The anion in turn forms two hydrogen bonds, O - H⋯O with the anion as donor and N - H⋯O with the anion as acceptor, to generate an R 2 2(10) loop. Each HSO 4 - anion connects two chlordiazepoxide moieties of the same chirality.

  • 81. Dispenza, C.
    et al.
    Spadaro, G.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Radiation Engineering of Multifunctional Nanogels2016In: Topics in Current Chemistry, ISSN 2365-0869, Vol. 374, no 5, article id 69Article, review/survey (Refereed)
    Abstract [en]

    Nanogels combine the favourable properties of hydrogels with those of colloids. They can be soft and conformable, stimuli-responsive and highly permeable, and can expose a large surface with functional groups for conjugation to small and large molecules, and even macromolecules. They are among the very few systems that can be generated and used as aqueous dispersions. Nanogels are emerging materials for targeted drug delivery and bio-imaging, but they have also shown potential for water purification and in catalysis. The possibility of manufacturing nanogels with a simple process and at relatively low cost is a key criterion for their continued development and successful application. This paper highlights the most important structural features of nanogels related to their distinctive properties, and briefly presents the most common manufacturing strategies. It then focuses on synthetic approaches that are based on the irradiation of dilute aqueous polymer solutions using high-energy photons or electron beams. The reactions constituting the basis for nanogel formation and the approaches for controlling particle size and functionality are discussed in the context of a qualitative analysis of the kinetics of the various reactions.

  • 82. Dispenza, Clelia
    et al.
    Grimaldi, Natascia
    Sabatino, Maria Antonietta
    Soroka, Inna L.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Radiation-Engineered Functional Nanoparticles in Aqueous Systems2015In: Journal of Nanoscience and Nanotechnology, ISSN 1533-4880, E-ISSN 1533-4899, Vol. 15, no 5, p. 3445-3467Article, review/survey (Refereed)
    Abstract [en]

    Controlled synthesis of nanoscalar and nanostructured materials enables the development of novel functional materials with fine-tuned optical, mechanical, electronic, magnetic, conductive and catalytic properties that are of use in numerous applications. These materials have also found their potential use in medicine as vehicles for drug delivery, in diagnostics or in combinations thereof. In principle, nanoparticles can be divided into two broad categories, organic and inorganic nanoparticles. For both types of nanoparticles there are numerous possible synthetic routes. Considering the large difference in nature of these materials and the elementary reactions involved in the synthetic routes, most manufacturing techniques are complex and only suitable for one type of particle. Interestingly, radiation chemistry, i.e., the use of ionizing radiation from radioisotopes and accelerators to induce nanomaterials or chemical changes in materials, has proven to be a versatile tool for controlled manufacturing of both organic and inorganic nanoparticles. The advantages of using radiation chemistry for this purpose are many, such as low energy consumption, minimal use of potentially harmful chemicals and simple production schemes. For medical applications one more advantage is that the material can be sterile as manufactured. Radiation-induced synthesis can be carried out in aqueous systems, which minimizes the use of organic solvents and the need for separation and purification of the final product. The radiation chemistry of water is well known, as are the various ways of fine-tuning the reactivity of the system towards a desired target by adding different solutes. This, in combination with the controllable and adjustable irradiation process parameters, makes the technique superior to most other chemical methods. In this review, we discuss the fundamentals of radiation chemistry and radiation-induced synthesis of nanoparticles in aqueous solutions. The impact of dose and dose rate as well as of controlled addition of various solutes on the final particle composition, size and size distribution are described in detail and discussed in terms of reaction mechanism and kinetics.

  • 83.
    Dispenza, Clelia
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. Università Degli Studi di Palermo, Italy.
    Sabatino, M. A.
    Grimaldi, N.
    Mangione, M. R.
    Walo, M.
    Murugan, Eagambaram
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    On the origin of functionalization in one-pot radiation synthesis of nanogels from aqueous polymer solutions2016In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 4, p. 2582-2591Article in journal (Refereed)
    Abstract [en]

    Radiation-engineered poly(N-vinyl pyrrolidone) nanogels are very interesting biocompatible nanocarriers for i.v. administration of therapeutics and contrast agents for bioimaging. The manufacturing process is fast and effective, it grants excellent control of particle size and simultaneous sterilization of the formed nanogels. Interestingly, primary amino groups and carboxyl groups, useful for (bio) conjugation, are also formed in a dose-dependent fashion. In this paper, by means of both numerical simulations and experiments, the origin of nanogel size control and functionalization is investigated. This understanding offers a new dimension for the design and production of radiation-sculptured multifunctional nanocarriers from aqueous solutions of polymers.

  • 84.
    Dong, Hai
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Rahm, Martin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Thota, Niranjan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Deng, Lingquan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Brinck, Tore
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Control of the ambident reactivity of the nitrite ion2013In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 11, no 4, p. 648-653Article in journal (Refereed)
    Abstract [en]

    In previous studies, it was reported that a neighbouring equatorial ester group is essential for a good yield of nitrite-mediated triflate inversion, whereas with neighbouring benzyl ether groups or axial ester groups, mixtures are generally produced. In the present study, the origin of this difference was addressed. The ambident reactivity of the nitrite ion has been found to be the cause of the complex product formation observed, which can be controlled by a neighbouring equatorial ester group. Both N-attack and O-attack occur in the absence of the ester group, whereas O-attack is favoured in its presence. A neighbouring group assistance mechanism is proposed, in addition to steric effects, based on secondary interactions between the neighbouring ester group and the incoming nucleophile. High-level quantum mechanical calculations were carried out in order to delineate this effect. The theoretical results are in excellent agreement with experiments, and suggest a catalytic role for the neighbouring equatorial ester group.

  • 85.
    Duan, Lele
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Wang, Lei
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Inge, A. Ken
    Fischer, Andreas
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Zou, Xiaodong
    Sun, Licheng
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Insights into Ru-Based Molecular Water Oxidation Catalysts: Electronic and Noncovalent-Interaction Effects on Their Catalytic Activities2013In: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 52, no 14, p. 7844-7852Article in journal (Refereed)
    Abstract [en]

    A series of Ru-bda water oxidation catalysts [Ru(bda)L-2] (H(2)bda = 2,2'-bipyridine-6,6'-dicarboxylic acid; L = [HNEt3][3-SO3-pyridine], 1; 4-(EtOOC)-pyridine, 2; 4-bromopyridine, 3; pyridine, 4; 4-methoxypyridine, 5; 4-(Me2N)-pyridine, 6; 4-[Ph(CH2)(3)]-pyridine, 7) were synthesized with election-donating/-withdrawing groups and hydro-philic/hydrophobic groups in the axial ligands. These complexes were characterized by H-1 NMR spectroscopy, high-resolution mass spectrometry, elemental analysis, and electrochemistry. In addition, complexes 1 and 6 were further identified by single crystal X-ray crystallography, revealing a highly distorted octahedral configuration of the Ru coordination sphere. All of these complexes are highly active toward Ce-IV-driven (Ce-IV = Ce(NH4)(2)(NO3)(6)) water oxidation with oxygen evolution rates up to 119 mols of O-2 per mole of catalyst per second. Their structure-activity relationship was investigated. Electron-withdrawing and noncovalent interactions (attraction) exhibit positive effect on the catalytic activity of Ru-bda catalysts.

  • 86.
    Dunér, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Grafted Molecular Layers for Control of Surface Properties2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The goal of this thesis work was to develop responsive surface grafted brushlayers for control of surface properties and to gain insights in the molecular mechanisms that control these properties. Three types of grafted layers were investigated, as outlined below. In the first system studied, poly(AAc) was synthesized by a grafting from approach, utilizing a photopolymerization reaction from a macroinitiator cast onto QCM substrates. The responsiveness in terms of frequency change, Δf, of the resulting brushes to changes in bulk pH was studied with QCM. Further, the friction properties of poly(AAc) was elucidated with colloidal probe AFM as a function of pH and counterion valency. High friction (μ=0.27) was found in presence of CaCl2 at high pH (7.5), but not under any other condition explored. It was concluded that the high friction was due to intralayer COO--Ca2+--OOC bridges. QCM-D was utilized for studying viscoelastic properties of growing poly(AAc) films during in situ photopolymerization. By Voigt modeling, the thickness, shear elasticity and shear viscosity were extracted. These parameters were observed to undergo sudden transitions at a critical thickness, and from this thickness the grafting density of the growing poly(AAc) layers was determined. In addition, the sensitivity to changes in Δf and ΔD with respect to the thickness of the poly(AAc) films was investigated, and the results showed that high sensitivity in ΔD is retained at higher film thicknesses than for Δf, and that the sensitivity with respect to noise can significantly alter the thickness that is best suited forthe study of viscoelastic changes in sensor applications. The work with QCM-D also involved the detection of structural variations within a thick brush layer of poly(AAc). Since lower overtones have higher penetration depth, these frequencies sense polymer segments further out in the brush. It was found that the apparent pKa of the poly(AAc) was higher for lower overtones, indicating therelative ease of acid dissociation in segments further out in the polyelectrolytebrush. In the second system studied, phenylethylamine (PEA) was electrografted to flatsurfaces of glassy carbon (GC). The nanomechanical properties, such as topography, deformation, adhesion and dissipation, were investigated using PeakForce quantitative nanomechanical mapping (QNM). One main finding is that globular domains of 40 to 50 nm indiameter appear in the electrografted PEA layer. They are assigned to clusters of PEA formed due to less rapid reactions between radicals and the GC surface compared to reactions with already grafted PEA. The interactions between the PEA layer and a silica sphere were further investigated by surface force measurements. A main finding is that the PEA surfaces were heavily charge regulated due to the limited net charge of the PEA layer compared to that of silica. In the third system studied, the mechanical response of polyelectrolytes as a function of applied load, probing angle and pH was investigated with PeakForce QNM. The used polyelectrolyte was poly(2-dimethylaminoethyl methacrylate)(PDMAEMA) with pKa of 6.5 to 7.5 and grafted to silica nanoparticles. While most research on polyelectrolyte brushes is conducted by employing flat and smooth surfaces, with a roughness on the nanometer scale, real surfaces are rarely ever ideally flat but rather they possess topographic irregularities on nano- and micro-scales, which locally imparts high curvatures. The spherical geometry of the core-shell nanoparticles serves as a model for real surfaces with respect to topographical irregularities of real surfaces. The nanoscale brushes were probed with an ultrasharp AFM tip, providing nanoscale resolution of topography, deformation, adhesion and dissipation. It was found that the mechanical response of the polyelectrolyte corona is dependent on the applied load and the polar angle of the tip-brush interaction. All nanomechanical data show a non-monotonic variation with horizontal position, and the peak values are shifted in magnitude and position as a function of peak force. The effect of pH on deformation was further investigated. The results showed that the brush is more resistant against compression over the centre than it is to deflection at larger horizontal positions, and this effect is amplified by charging the brush. This work provided understanding of the direction dependence of the mechanical properties and is relevant for the design of brush boundary lubricating agents for rough surfaces, where the polymer chains are both being bent and compressed under the influence of load and shear.

  • 87.
    Dunér, Gunnar
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Thormann, Esben
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Dédinaité, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Acid dissorciation constant gradients in a thick viscoelastic film determined by dissipation monitoring using quartz crystal microbalanceManuscript (preprint) (Other academic)
  • 88.
    Dunér, Gunnar
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Thormann, Esben
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Dédinaité, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Frequency and dissipation measurements of in situ grafted poly(acrylic acid): a study of sensitivity and signal-to-noise ratio from thin to thick viscoelastic regimeManuscript (preprint) (Other academic)
  • 89.
    Dunér, Gunnar
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Thormann, Esben
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Dédinaité, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Matyjaszewski, Krzysztof
    Tilton, Robert D.
    Nanomechanical mapping of a high curvature polymer brush grafted from a rigid nanoparticle2012In: Soft Matter, ISSN 1744-683X, E-ISSN 1744-6848, Vol. 8, no 32, p. 8312-8320Article in journal (Refereed)
    Abstract [en]

    Analysis of interaction forces when probing a silica core-polyelectrolyte brush shell nanoparticle, adsorbed on a silica substrate and bathed by aqueous electrolyte solution, with an ultrasharp atomic force microscopy (AFM) tip provides a spatially resolved map of heterogeneous mechanical properties across the nanoparticle. The deformation of the brush is mainly compressive when probed directly above the nanoparticle centre and mainly deflective when probed at a finite horizontal distance away from the centre. The brush is significantly stiffer against compression than against deflection, and ionization of the brush has a greater stiffening effect against compression than deflection. Whereas a height image of the core-shell nanoparticle was unremarkable, showing a monotonic decrease in height with increasing horizontal distance from the centre, brush deformation, energy dissipation and adhesion displayed local minima over the centre and maxima at a finite horizontal distance away from the centre, corresponding to a position near the rigid core nanoparticle edge. The different response to brush deformation depending on the angle of probing is relevant to the interactions of brush-decorated macroscopic surfaces with submicrometer roughness and to the interactions of brush-decorated nanoparticles with ultrafine structures in their environments.

  • 90.
    Dunér, Gunnar
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Thormann, Esben
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Ramström, Olof
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Dédinaité, Andra
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Determination of grafting density of poly(acrylic acid) in a grafting: from approach using quartz crystal microbalance with dissipationManuscript (preprint) (Other academic)
  • 91.
    Dvinskikh, Sergey V.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Pulsed-Field-Gradient NMR Study of Anisotropic Molecular Translational Diffusion in nOCB Liquid Crystals2013In: Applied Magnetic Resonance, ISSN 0937-9347, E-ISSN 1613-7507, Vol. 44, no 1-2, p. 169-180Article in journal (Refereed)
    Abstract [en]

    Pulsed-field-gradient nuclear magnetic resonance (NMR) combined with magic echo decoupling is applied to study anisotropic diffusion in samples with strong static dipolar spin interactions. The approach, due to its moderate demands on the NMR hardware, can be implemented on standard commercial equipment for routine diffusion studies of liquid crystals. Using a microimaging probe, measurement of diffusion in arbitrary spatial direction is possible. Hence, the principal components of the diffusion tensor are directly obtained. Anisotropic diffusion is investigated in the thermotropic mesophases of a homologous series of nOCB liquid crystals and an analogous compound with hydroxyl groups. The geometric average diffusion coefficient changes continuously at the isotropic-nematic phase transition. Experimental data are described in terms of the molecular translation models in the nematic phase and for the second-order nematic-smectic A phase transition. The diffusion anisotropy is higher for the sample with terminal hydroxyl groups suggesting significant molecular association via hydrogen bonding.

  • 92.
    Dvinskikh, Sergey V.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Anisotropic self-diffusion in nematic, smectic-A, and reentrant nematic phases2012In: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics, ISSN 1539-3755, E-ISSN 1550-2376, Vol. 86, no 3, p. 031704-Article in journal (Refereed)
    Abstract [en]

    The nature of the reentrant nematic phase has been actively investigated both experimentally and theoretically during the past few decades. Most studies concluded that, as concerning molecular dynamics, a reentrant nematic phase is essentially analogous to a conventional nematic one. Recent computer simulations [Mazza et al., Phys. Rev. Lett. 105, 227802 (2010)], however, predicted molecular translational self-diffusion along the phase director that was dominated by a collective transport mode and was, relative to that observed in a conventional nematic phase, enhanced by an order of magnitude. In the present work, the principal components of the diffusion tensor in a reentrant nematic phase are determined experimentally and compared to those in conventional nematic and smectic-A phases. We find that the temperature dependence of the translational diffusion in the two nematic phases, within experimental error, follows a uniform trend and can be adequately described in terms of available diffusion models in nematics. Hence, we find no evidence for enhanced diffusion but confirm instead the similarity of conventional and reentrant nematic phases with respect to molecular translational dynamics.

  • 93. Ellis-Gibbings, Lilian
    et al.
    Johansson, Viktor
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Walsh, Rick B.
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Quinton, Jamie S.
    Andersson, Gunther G.
    Formation of N719 Dye Multilayers on Dye Sensitized Solar Cell Photoelectrode Surfaces Investigated by Direct Determination of Element Concentration Depth Profiles2012In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 28, no 25, p. 9431-9439Article in journal (Refereed)
    Abstract [en]

    The structure of the dye layer adsorbed on the titania substrate in a dye-sensitized solar cell is of fundamental importance for the function of the cell, since it strongly influences the injection of photoelectrons from the excited dye molecules into the titania substrate. The adsorption isotherms of the N719 ruthenium-based dye were determined both with a direct method using the depth profiling technique neutral impact collision ion scattering spectroscopy (NICISS) and with the standard indirect solution depletion method. It is found that the dye layer adsorbed on the titania surface is laterally inhomogeneous in thickness and there is a growth mechanism already from low coverage levels involving a combination of monolayers and multilayers. It is also found that the amount of N719 adsorbed on the substrate depends on the titania structure. The present results show that dye molecules in dye-sensitized solar cells are not necessarily, as presumed, adsorbed as a self-assembled monolayer on the substrate.

  • 94.
    Elwinger, Fredrik
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Characterizing Chromatography Media: NMR-based Approaches2017Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Liquid chromatography is an essential technique in manufacturing biopharmaceuticals where it is used on all scales from analytical applications in R&D to full-scale production. In chromatography the target molecule, typically a protein, is separated and purified from other components and contaminants. Separation is based on different affinities of different molecules for the chromatographic medium and the physical and chemical properties of the latter determine the outcome. Controlling and designing those properties demand efficient analytical techniques.

    In this thesis the approach was to develop characterization methods based on nuclear magnetic resonance (NMR) spectroscopy for the assessment of various important physico-chemical properties. The rationale behind this strategy was that the versatility of NMR – with its chemical and isotopic specificity, high dynamic range, and direct proportionality between the integral intensity of the NMR signal and the concentration of spin-bearing atomic nuclei (e.g., 1H, 13C, 31P and 15N) – often renders it a very good choice for both qualitative and quantitative evaluations.

    These characteristics of NMR enabled us to develop two quantification methods for chromatography-media ligands, the functional groups that provide the specific interactions for the molecules being separated. Furthermore, a new method for measuring the distribution of macromolecules between the porous chromatographic beads and the surrounding liquid was established. The method, which we have named size-exclusion quantification (SEQ) NMR, utilizes the fact that it is possible to assess molecular size distribution from corresponding distribution of the molecular self-diffusion coefficient where the latter is accessible by NMR. SEQ-NMR results can also be interpreted in terms of pore-size distribution within suitable models. Finally, we studied self-diffusion of small molecules inside the pores of chromatographic beads. The results provided new insights into what affects the mass transport in such systems.

    The methods presented in this thesis are accurate, precise, and in many aspects better than conventional ones in terms of speed, sample consumption, and potential for automation. They are thus important tools that can assist a better understanding of the structure and function of chromatography media. In the long run, the results in this project may lead, via better chromatographic products, to better drugs and improved health.

  • 95.
    Elwinger, Fredrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. GE Healthcare Biosci AB.
    Dvinskikh, Sergey V.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    C-13 SPE MAS measurement of ligand concentration in compressible chromatographic beads2015In: Magnetic Resonance in Chemistry, ISSN 0749-1581, E-ISSN 1097-458X, Vol. 53, no 8, p. 572-577Article in journal (Refereed)
    Abstract [en]

    A method for measuring the ligand concentration in heterogeneous materials like chromatography media is described. In this method, C-13 single pulse excitation magic angle spinning NMR experiment with broadband H-1 decoupling is used to determine the peak integrals for a butyl ligand in the spectrum of a dried chromatography medium. Within a carefully controlled protocol, those integrals compared with that of the internal reference compound dimethyl sulfone provide the required volume concentration with an accuracy of ca 2%. The effects of temperature, degree of hydration, and other experimental parameters are discussed. Copyright (C) 2015 The Authors. Magnetic Resonance in Chemistry published by John Wiley & Sons Ltd.

  • 96.
    Elwinger, Fredrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry. GE Healthcare Biosci AB, Sweden.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    High-resolution magic angle spinning H-1 NMR measurement of ligand concentration in solvent-saturated chromatographic beads2016In: Magnetic Resonance in Chemistry, ISSN 0749-1581, E-ISSN 1097-458X, Vol. 54, no 4, p. 291-297Article in journal (Refereed)
    Abstract [en]

    A method based on H-1 high-resolution magic angle spinning NMR has been developed for measuring concentration accurately in heterogeneous materials like that of ligands in chromatography media. Ligand concentration is obtained by relating the peak integrals for a butyl ligand in the spectrum of a water-saturated chromatography medium to the integral of the added internal reference. The method is fast, with capacity of 10min total sample preparation and analysis time per sample; precise, with a reproducibility expressed as 1.7% relative standard deviation; and accurate, as indicated by the excellent agreement of derived concentration with that obtained previously by C-13 single-pulse excitation MAS NMR. The effects of radiofrequency field inhomogeneity, spin rate, temperature increase due to spinning, and distribution and re-distribution of medium and reference solvent both inside the rotor during spinning and between bulk solvent and pore space are discussed in detail.

  • 97.
    Elwinger, Fredrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Pourmand, Payam
    KTH, School of Chemical Science and Engineering (CHE), Centres, Industrial NMR Centre. KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymeric Materials.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Centres, Industrial NMR Centre. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Diffusive Transport in Pores. Tortuosity and Molecular Interaction with the Pore Wall2017In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 121, no 25, p. 13757-13764Article in journal (Refereed)
    Abstract [en]

    The self-diffusion of neat water, dimethyl sulfoxide (DMSO), octanol, and the molecular components in a water-DMSO solution was measured by H-1 and H-2 NMR diffusion experiments for those fluids imbibed into controlled pore glasses (CPG). Their highly interconnected structure is scaled by pore size and shows invariant pore topology independent of the size. The nominal pore diameter of the explored CPGs varied from 7.5 to 72.9 nm. Hence, the about micrometer mean-square diffusional displacement during the explored diffusion tithes was much larger than the individual pore size, and the experiment yielded the average diffusion coefficient Great care was taken to establish the actual pore: volumes of the CPGs. Transverse relaxation experiments processed by inverse Laplace transformation were performed to verify that the liquids explored filled exactly the available pore volume. Relative to the respective diffusion coefficients obtained in bulk phases, we observe a reduction in the diffusion coefficient that is independent of pore size for the larger pores and becomes stronger toward the smaller pores. Geometric tortuosity governs the behavior at larger pore sizes, while the interaction with pore walls becomes the dominant factor at our smallest pore diameter. Deviation from the trends predicted by the Renkin equation indicates that the interaction with the pore wall is not a just simple steric one but is in part dependent on the specific features of the molecules explored here.

  • 98.
    Elwinger, Fredrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Pourmand, Payam
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Furó, István
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Diffusive transport in pores. Tortuosity and molecular interaction with the pore wallManuscript (preprint) (Other academic)
    Abstract [en]

    The self-diffusion of neat water, dimethylsulfoxide (DMSO), octanol and the molecular components in a water-DMSO solution were measured by 1H and 2H NMR diffusion experiments for those fluids imbibed into Controlled Pore Glasses (CPG). Their highly interconnected structure is scaled by pore size and shows the some pore topology independently of the size. The nominal pore diameter of the explored CPGs varied from 7.5 nm to 72.9 nm. Hence, the ∼μm mean-square diffusional displacement during the explored diffusion times was much larger than the individual pore size. Great care was taken to establish the actual pore volumes of the CPGs. In addition, transverse relaxation experiments processed by Inverse Laplace Transformation were performed to verify that the liquids explored filled exactly the available pore volume. Relative to the respective diffusion coefficients obtained in bulk phases, we observe a reduction in the diffusion coefficient that is independent of pore sizes for the larger pores and becomes larger towards the smaller pores. Geometric tortuosity governs the behavior at larger pore sizes while the interaction with pore walls becomes the dominant factor at our smallest pore diameter. The interaction with the pore wall is not just simple steric one but must in part be dependent on the specific features of the molecules explored here.

  • 99.
    Elwinger, Fredrik
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Wernersson, Jonny
    Furó, István
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    SEQ-NMR: A new tool for measuring distribution coefficients and pore size in chromatography mediaManuscript (preprint) (Other academic)
    Abstract [en]

    We present a new method, SEQ-NMR (size-exclusion quantification NMR spectroscopy) for measuring equilibrium distribution coefficients, Keq, in chromatography media. The same method is also generally applicable to measure pore sizes in any porous media. Keq versus probe size, the selectivity curve, is obtained by equilibrating a chromatographic medium with a solution of polymers with a broad size distribution. The solution before and after equilibration is analyzed with NMR diffusion experiments. The joint least-squares analysis of the two diffusion attenuation curves under suitable constraints provides the extent by which the different polymer fractions are diluted upon equilibration that in turn yields the selectivity curve. The relation of the applied procedure to Inverse Laplace transformation is clarified. Simulations probe the performance of the method, in particular with respect to signal-to-noise ratio (SNR) and other parameters used in the data inversion process. The method is demonstrated experimentally using dextran polymers and the chromatographic medium Sephacryl™ S-200 High Resolution for which it yields, within a cylindrical pore model, 6.9 nm for the average hydrated pore size. Comparison is made to the analysis of the same system with inverse size-exclusion chromatography (ISEC). Advantages of the method, primarily that in speed, potential for automation, and small sample size, are discussed.

  • 100. El-Zohry, Ahmed M.
    et al.
    Cong, Jiayan
    KTH.
    Karlsson, Martin
    Kloo, Lars
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Applied Physical Chemistry.
    Zietz, Burkhard
    Ferrocene as a rapid charge regenerator in dye-sensitized solar cells2016In: Dyes and pigments, ISSN 0143-7208, E-ISSN 1873-3743, Vol. 132, p. 360-368Article in journal (Refereed)
    Abstract [en]

    Using the reductive power of the ferrocene moiety (Fc), an ultrafast regeneration step via a covalent attachment of a Fc moiety to an organic triphenylamine-based dye (L1) when adsorbed on TiO2 is highlighted. Two modified dyes with one and two Fc moieties attached (L1Fc, and L1Fc2), respectively, were synthesized by addition to the L1 dye. These dyes have been studied spectroscopically using ultrafast transient absorption spectroscopy in the visible and the infrared (IR) regions. In acetonitrile, the results show an ultrafast excited state quenching of the modified dyes due to an expected electron transfer process from the Fc(s) to L1. Adsorbed onto TiO2, an electron transfer process is also detected from Fc to the oxidized dye (L1(+)). Despite the occurrence of an ultrafast regeneration step, the solar cell performance does not improve by the attachment of Fc(s) to the dye L1. Transient absorption measurements in the IR region revealed a fast electron recombination process to the Fc(+) moiety on an average time scale of ca. 300 ps, outcompeting the >12 ns process to L1(+). The reasons for the observed considerably faster recombination rate to Fc(+) than to L1(+) are discussed in detail. This study provides deep spectroscopic insights for such organic dyes utilized to afford ultrafast regeneration step without showing high performance in photovoltaic devices. In addition, this study will improve our understandings for the triangular relationship between the molecular design, electron kinetics, and the performance in photovoltaic devices. (C) 2016 Elsevier Ltd. All rights reserved.

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