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  • 1.
    Andrén, Oliver C. J.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Walter, Marie V.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Yang, Ting
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Hult, Anders
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Malkoch, Michael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Multifunctional Poly(ethylene glycol): Synthesis, Characterization, and Potential Applications of Dendritic-Linear-Dendritic Block Copolymer Hybrids2013In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 46, no 10, p. 3726-3736Article in journal (Refereed)
    Abstract [en]

    Emerging dendritic-linear-dendritic (DLD) hybrids that possess synergetic properties of linear and highly functional branched dendritic polymers are becoming important macromolecular scaffolds in fields ranging from biomedicine to nanotechnology. By exploiting pseudo-one-step polycondensation reactions, a facile and scalable synthetic methodology for the construction of highly functional DLDs has been developed. A library of three sets of DLDs exhibiting a hydrophilic linear PEG core with covalently attached hyperbranched bis-MPA blocks was synthesized up to the seventh generation with 256 reactive peripheral hydroxyl groups. The degree of branching for the hybrids was found between 0.40 and 0.59 with dispersities ranging from 1.03 to 1.88. The introduction of hyperbranched components resulted in control over or even full disruption of the crystallinity of the PEG. Postfunctionalizations of the peripheral hydroxyl groups with azides, allyls, and ATRP initiators yielded reactive intermediates. These intermediates were successfully assessed through UV-initiated thiol-ene coupling reactions for the synthesis of charged hybrids. ATRP of styrene from the pheriphery afforded amphiphilic macromolecules. Finally, their scaffolding capacity was evaluated for the fabrication of 3D networks, i.e, novel dendritic hydrogels and highly ordered breath figures.

  • 2.
    Antoni, Per
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Robb, Maxwell J.
    Campos, Luis
    Montanez, Maria
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hult, Anders
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Malkoch, Michael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hawker, Craig J.
    Pushing the Limits for Thiol-Ene and CuAAC Reactions: Synthesis of a 6th Generation Dendrimer in a Single Day2010In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 43, no 16, p. 6625-6631Article in journal (Refereed)
    Abstract [en]

    Dendrimer synthesis should not be tedious and time-consuming. By utilizing an AB(2)-CD2 approach and having orthogonal, "clickable" groups on each monomer, the time for dendrimer assembly can be drastically reduced. This was shown by preparation of a sixth generation dendrimer from starting monomer units in a single day.

  • 3.
    Bergenudd, Helena
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Nuclear Chemistry.
    Coullerez, Geraldine
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Nuclear Chemistry.
    Jonsson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Nuclear Chemistry.
    Malmström, Eva E.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Solvent Effects on ATRP of Oligo(ethylene glycol) Methacrylate. Exploring the Limits of Control2009In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 42, no 9, p. 3302-3308Article in journal (Refereed)
    Abstract [en]

    Five copper complexes in combination with six monomer-solvent mixtures have been used to investigate the solvent effects oil ATRP of oligo(ethylene glycol) methacrylate (OEGMA). The redox properties of the copper complexes in OEGMA-solvent mixtures and the apparent rate constants (k(p)(app)) for ATRP of OEGMA were correlated to the degree of control over the polymerizations. Based on this correlation, a general discussion of the limits of control in ATRIP is carried out. One of the key parameters for control in ATRP is the propagation rate constant, making the choice of monomer essential for the design of ail ATRP system. Also, the solvent effects oil the ATRP equilibrium constant (K-ATRP) affect the limit of control (i.e., the apparent rate constant above which control is lost). The choice of copper complex is also more important than the choice of solvent for the design of a well-controlled ATRP system.

  • 4.
    Brouzet, Christophe
    et al.
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Mittal, Nitesh
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Lundell, Fredrik
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Characterizing the Orientational and Network Dynamics of Polydisperse Nanofibers on the Nanoscale2019In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 52, no 6, p. 2286-2295Article in journal (Refereed)
    Abstract [en]

    Polydisperse fiber networks are the basis of many natural and manufactured structures, ranging from high-performance biobased materials to components of living cells and tissues. The formation and behavior of such networks are given by fiber properties such as length and stiffness as well as the number density and fiber-fiber interactions. Studies of fiber network behavior, such as connectivity or rigidity thresholds, typically assume monodisperse fiber lengths and isotropic fiber orientation distributions, specifically for nano scale fibers, where the methods providing time-resolved measurements are limited. Using birefringence measurements in a microfluidic flow-focusing channel combined with a flow stop procedure, we here propose a methodology allowing investigations of length-dependent rotational dynamics of nanoscale polydisperse fiber suspensions, including the effects of initial nonisotropic orientation distributions. Transition from rotational mobility to rigidity at entanglement thresholds is specifically addressed for a number of nanocellulose suspensions, which are used as model nanofiber systems. The results show that the proposed method allows the characterization of the subtle interplay between Brownian diffusion and nanoparticle alignment on network dynamics.

  • 5. Busson, P.
    et al.
    Ortegren, J.
    Ihre, H.
    Gedde, Ulf W.
    KTH, Superseded Departments, Polymer Technology.
    Hult, Anders
    KTH, Superseded Departments, Polymer Technology.
    Andersson, G.
    Ferroelectric liquid crystalline dendrimers: Synthesis, thermal behavior, and electrooptical characterization2001In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 34, no 5, p. 1221-1229Article in journal (Refereed)
    Abstract [en]

    The preparation and characterization of a series of novel ferroelectric liquid crystalline dendrimers are presented. End-capping of 1-, 2-, and 3-generation dendrimers based on 2,2-bis(hydroxymethyl)propionic acid with mesogens gave surface-functionalized liquid crystalline compounds with 6, 12, and 24 mesogen-containing units, respectively. 4 -((R)-1-Methylheptyloxy)phenyl 4-(4 '-[10(hydroxycarbonyl)decyloxyl phenyl)benzoate was synthesized and used as a mesogen-containing unit. The purity and structure of each compound were determined by H-1 NMR spectroscopy, size exclusion chromatography, and elemental analysis. Differential scanning calorimetry and optical microscopy were used to investigate the mesomorphic properties of the mesogen-functionalized dendrimers. The materials displayed a variety of mesophases, including the smectic C* phase. All the liquid crystalline dendrimers showed ferroelectricity, and tilt angle and spontaneous polarization measurements were performed. The obtained results show that the ferroelectric properties of the materials are independent of the generation number of the dendritic scaffold.

  • 6. Busson, P.
    et al.
    Ortegren, J.
    Ihre, H.
    Gedde, Ulf W.
    KTH, Superseded Departments, Polymer Technology.
    Hult, Anders
    KTH, Superseded Departments, Polymer Technology.
    Andersson, G.
    Eriksson, A.
    Lindgren, M.
    Preparation of mesogen-functionalized dendrimers for second-order nonlinear optics2002In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 35, no 5, p. 1663-1671Article in journal (Refereed)
    Abstract [en]

    Liquid crystalline dendrimers with peripheral mesogen-containing units have been prepared. Multistep synthesis with several selective reactions was used in the preparation of the mesogen-containing molecules, 4-[10-(hydroxycarbonyl)decyloxy]phenyl 4-[4'-(2-(R)-octyloxy)-3'-nitrophenyl]benzo ate and 4-[10-(hydroxycarbonyl)decyloxy]biphenyl 4-[4'-(2-(R)-octyloxy)-3'-nitrophenyl]benzoate. Both molecules possessed an electron-accepting nitro group placed perpendicular to the long axis of the molecules in order to enhance the nonlinear optical activity. A second generation hydroxyl functional aliphatic dendrimer based on the dihydroxy acid, 2,2-bis(hydroxymethyl)propionic acid, was used as dendritic scaffold and was subsequently functionalized with the aforementioned groups. The purity and structure of the two liquid crystalline dendrimers were determined by H-1 NMR spectroscopy, size exclusion chromatography, and elemental analysis. The synthesis of both the mesogen-containing units and the liquid crystalline dendrimers is described in detail. Investigation of the liquid crystalline properties of the materials by differential scanning calorimetry and optical microscopy showed that they exhibited different mesophases, including the chiral smectic C phase. Ferroelectric switching was observed in this tilted phase, and electrooptical properties, including tilt angle and spontaneous polarization measurements, were investigated. Finally, the nonlinear optical properties of one of the materials were preliminary characterized.

  • 7.
    Carlmark, Anna
    et al.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Malmström, Eva E
    KTH, Superseded Departments, Fibre and Polymer Technology.
    ATRP of dendronized aliphatic macromonomers of generation one, two, and three2004In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 37, no 20, p. 7491-7496Article in journal (Refereed)
    Abstract [en]

    Atom transfer radical polymerization (ATRP) of dendritic, aliphatic macromonomers has been investigated. The macromonomers were based on acrylate functionalized 2,2-bis(methylol)propionic acid (bis-MPA) dendrons, with a flexible spacer of 10 carbons incorporated in the structure in between the polymerizable group and the dendritic wedge. Dendronized polymers of generation one, two, and three were successfully synthesized by ATRP. The polymerizations proceeded until over 80% conversion was reached, while maintaining control over polydispersity index (PDI). Plots of ln([M](0)/[M]) vs time for the polymerization of all three macromonomers showed a linear dependence, indicating that the number of propagating radicals in the reaction solution was constant throughout the reaction, when ethyl 2-bromopropionate (EBrP) was used as an initiator (i.e., radical termination was negligible). All of the resulting polymers had low PDI values and molecular weight close to the theoretical ones. The products were analyzed by H-1 and C-13 NMR spectroscopies, size exclusion chromatography (SEC), differential scanning calorimetry (DSC), and matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF).

  • 8. Chen, Gaojian
    et al.
    Tao, Lei
    Mantovani, Giuseppe
    Geng, J.
    Nyström, Daniel
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Haddleton, David M.
    A modular click approach to glycosylated polymeric beads: Design, synthesis and preliminary lectin, recognition studies2007In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 40, no 21, p. 7513-7520Article in journal (Refereed)
    Abstract [en]

    Covalent immobilization of a range of carbohydrate derivatives onto polymeric resin beads is described. Copper-catalyzed Huisgen [2 + 3] cycloaddition (often termed click chemistry) was used to graft mannose-containing azides to complementarily functionalized alkyne surfaces, namely (a) Wang resin or (b) Rasta particles consisting of a clickable alkyne polymer loose outer shell and a Wang resin inner core. For the second approach, Wang resin beads were first converted into immobilized living radical polymerization initiators with subsequent polymerization of trimethylsilanyl-protected propargyl methacrylate followed by deprotection with TBAF to yield the desired polyalkyne clickable scaffold. The appropriate (x-mannopyranoside azide was then clicked onto the bead to give a mannose functionalized Rasta resin. IR, gel-phase H-1 NMR, and elemental analysis have been used to characterize the modified resins. The binding abilities of these D-mannose-modified particles were subsequently tested using fluorescein-labeled Concanavalin A (Con A), a lectin that binds certain mannose-containing molecules. Preliminary results indicated that the novel glyco-hybrid materials presented in this work are able to efficiently recognize mannose-binding model lectins such as Con A, opening the way for their potential application in affinity chromatography, sensors, and other protein recognition/separation fields.

  • 9.
    Chen, Pan
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. Beijing Inst Technol, Sch Mat Sci & Engn, Beijing Engn Res Ctr Cellulose & Its Derivat, 5 South Zhongguancun St, Beijing 100081, Peoples R China..
    Terenzi, Camilla
    Wageningen Univ & Res, Lab Biophys, Stippeneng 4, NL-6708 WE Wageningen, Netherlands..
    Furo, Istvan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Wohlert, Jakob
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Quantifying Localized Macromolecular Dynamics within Hydrated Cellulose Fibril Aggregates2019In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 52, no 19, p. 7278-7288Article in journal (Refereed)
    Abstract [en]

    Molecular dynamics (MD) simulations of C-13 NMR longitudinal relaxation (T-1) distributions were recently established as a powerful tool for characterizing moisture adsorption in natural amorphous polymers. Here, such computational-experimental synergy is demonstrated in a system with intrinsically high structural heterogeneity, namely crystalline cellulose nanofibrils (CNFs) in highly hydrated aggregated state. In such a system, structure-function properties on the nanoscale remain largely uncovered by experimental means alone. In this work, broadly polydispersed experimental C-13 NMR T-1 distributions could be successfully reproduced in simulations and, for the first time, were decomposed into contributions from distinct molecular sources within the aggregated CNFs, namely, (i) the core and (ii) the less-accessible and accessible surface regions of the CNFs. Furthermore, within the surface groups structurally different sites such as (iii) residues with different hydroxymethyl orientations and (iv) center and origin chains could be discerned based on their distinct molecular dynamics. The MD simulations unravel a direct correlation between dynamical and structural heterogeneity at an atomistic-level resolution that cannot be accessed by NMR experiments. The proposed approach holds the potential to enable quantitative interpretation of NMR data from a range of multicomponent high-performance nanocomposites with significantly heterogeneous macromolecular structure.

  • 10.
    Fuoco, Tiziana
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Pappalardo, Daniela
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. Department of Science and Technology, University of Sannio, via dei Mulini 59/A, 82100 Benevento, Italy.
    Wistrand, Anna Finne
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Redox-Responsive Disulfide Cross-Linked PLA-PEG Nanoparticles2017In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 50, no 18, p. 7052-7061Article in journal (Refereed)
    Abstract [en]

    We have developed a strategy for the preparation of redox-responsive PEG PLA-based nanoparticles containing disulfide bonds that can be disassembled in the presence of cellular concentrations of glutathione. Functionalized poly-(lactide)s were prepared by ring-opening copolymerization of L-lactide and 3-methyl-6-(tritylthiomethyl)-1,4-dioxane-2,5-dione, a monomer bearing a pendant trityl-thiol group, followed by the postpolymerization modification of trityl-thiol into pyridyl disulfide groups. Polymeric networks composed of PLA and PEG blocks linked by disulfide bonds were prepared by a disulfide exchange reaction between the functionalized PLAs and telechelic PEG having thiol groups at both ends, HS-PEG-SH, in DMF. When dialyzed against water, they assembled into dispersible nanoparticles, with a flowerlike structure having a hydrophobic core and a hydrophilic shell, with sizes in the range 167-300 nm that are suitable for drug delivery. The effects of the number of functional groups, molecular weight, and concentration on the nanoparticle size were evaluated. The stability of the nanoparticles after dilution and the redox-responsive behavior in the presence of different concentrations of glutathione were assessed. The hydrophobic molecule Nile red could be encapsulated in the nanoparticles and then released in the presence of glutathione at cellular concentration.

  • 11. Gavelin, P.
    et al.
    Jannasch, P.
    Furo, Istvan
    KTH, Superseded Departments, Chemistry.
    Pettersson, E.
    Stilbs, Peter
    KTH, Superseded Departments, Chemistry.
    Topgaard, D.
    Soderman, O.
    Amphiphilic polymer gel electrolytes. 4. Ion transport and dynamics as studied by multinuclear pulsed field gradient spin-echo NMR2002In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 35, no 13, p. 5097-5104Article in journal (Refereed)
    Abstract [en]

    The transport dynamics in gel electrolytes based on amphiphilic polymers was found to be faster than in gel electrolytes based on corresponding nonamphiphilic polymers. The amphiphilic polymer studied was a polymethacrylate grafted with fluorocarbon and (EO)(9) side chains, and the nonamphiphilic one was a polymethacrylate carrying only (EO)(9) side chains. Self-diffusion coefficients of gel electrolytes based on the two polymers with different contents of 1 M lithium bis(trifluoromethylsulfonyl) imide (LiTFSI) salt in gamma-butyrolactone were determined by H-1, F-19, and Li-7 pulsed field gradient spin-echo NMR spectroscopy. The polymer self-diffusion coefficients showed that the amphiphilic polymer molecules diffused faster than the nonamphiphilic ones and seemed more intramolecularly aggregated than intermolecularly. At electrolyte contents above 43 wt %, the ion conductivity of the amphiphilic polymer gel electrolytes was higher than for the corresponding gel based on the nonamphiphilic polymer under identical conditions, as measured by impedance spectroscopy. Moreover, the lithium ion diffusion coefficient in the amphiphilic gel electrolytes was found to be significantly higher than that for corresponding gels based on the nonamphiphilic polymer, The higher ethylene oxide content of the nonamphiphilic polymer decreased the mobility of the lithium ions due to cooperative coordination of lithium ions by ether oxygens in comparison with gamma-BL. The TFSI anion diffusion was however approximately the same in the two gel systems. Consequently, the apparent lithium transference number (taudivided by) of the amphiphilic gels was higher by almost a factor of 3 as compared to that of the gels based on the nonamphiphilic polymer. A splitting of the TFSI signal in the F-19 NMR spectra suggested that the TFSI anions in the amphiphilic polymer gels were partly present in a solvent-rich environment and partly associated with the aggregates formed by the fluorinated side chains. This kind of splitting was not observed in the spectra of the gels based on the nonamphiphilic polymer. The association of TFSI anions to the aggregated fluorinated side chains may thus also play a role in increasing the value of taudivided by for the amphiphilic polymer gels.

  • 12. Geng, Lihong
    et al.
    Mittal, Nitesh
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Zhan, Chengbo
    Ansari, Farhan
    Sharma, Priyanka R.
    Peng, Xiangfang
    Hsiao, Benjamin S.
    Söderberg, Daniel
    KTH, School of Engineering Sciences (SCI), Mechanics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Understanding the Mechanistic Behavior of Highly Charged Cellulose Nanofibers in Aqueous Systems2018In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 51, no 4, p. 1498-1506Article in journal (Refereed)
    Abstract [en]

    Mechanistic behavior and flow properties of cellulose nanofibers (CNFs) in aqueous systems can be described by the crowding factor and the concept of contact points, which are functions of the aspect ratio and concentration of CNF in the suspension. In this study, CNFs with a range of aspect ratio and surface charge density (380-1360 mu mol/g) were used to demonstrate this methodology. It was shown that the critical networking point of the CNF suspension, determined by rheological measurements, was consistent with the gel crowding factor, which was 16. Correlated to the crowding factor, both viscosity and modulus of the systems were found to decrease by increasing the charge density of CNF, which also affected the flocculation behavior. Interestingly, an anomalous rheological behavior was observed near the overlap concentration (0.05 wt %) of CNF, at which the crowding factor was below the gel crowding factor, and the storage modulus (G') decreased dramatically at a given frequency threshold. This behavior is discussed in relation to the breakup of the entangled flocs and network in the suspension. The analysis of the mechanistic behavior of CNF aqueous suspensions by the crowding factor provides useful insight for fabricating high-performance nanocellulose-based materials.

  • 13. Griffiths, P. C.
    et al.
    Paul, A.
    Stilbs, Peter
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Petterson, E.
    Charge on poly(ethylene imine): Comparing electrophoretic NMR measurements and pH Titrations2005In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 38, no 8, p. 3539-3542Article in journal (Refereed)
  • 14.
    Guo, Baolin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Electroactive Hydrophilic Polylactide Surface by Covalent Modification with Tetraaniline2012In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 45, no 2, p. 652-659Article in journal (Refereed)
    Abstract [en]

    Covalent surface functionalization is presented as a versatile tool to increase the hydrophilicity and to introduce the electroactivity of polyester films. Acrylic acid and maleic anhydride were photografted onto a polylactide (PLA) surface with a "grafting from" method to increase the surface wettability, and the subsequent coupling of conductive aniline oligomer was used to introduce electroactivity to the PLA surface. The photopolymerization of maleic anhydride and acrylic acid and the coupling, of aniline tetramer (AT) were characterized by FT-IR, UV, and TGA. The surface morphology of the PLA surface before and after modification was examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). A medium hydrophilic surface of PLA was achieved by surface modification with maleic anhydride, acrylic acid, and AT. An electrically conductive surface was obtained after grafting with AT, and the conductivity increased with increasing AT content on the surface. The hydrophilic and electroactive surface of polyesters while retaining their bulk properties offers new possibilities in biomedical applications, such as bone, cartilage, neural, and cardiovascular tissue engineering.

  • 15.
    Guo, Baolin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Enhanced Electrical Conductivity by Macromolecular Architecture: Hyperbranched Electroactive and Degradable Block Copolymers Based on Poly(epsilon-caprolactone) and Aniline Pentamer2010In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 43, no 10, p. 4472-4480Article in journal (Refereed)
    Abstract [en]

    We present macromolecular architecture design as a useful tool to enhance the conductivity of degradable polymers. Linear and hyperbranched copolymers with electrical conductivity and biodegradability were synthesized by an "A(2) + B-n (n=2, 3, 4)" strategy using carboxyl-capped aniline pen tamer (CCAP) and branched poly(epsilon-caprolactone)s (PCLs) by coupling reactions. A more hydrophilic surface and lower crystallinity of the doped emeraldine state of aniline pentamer (EM A P) copolymer was achieved compared with PCLs, and TGA results demonstrated that the CCAP contents in the copolymers were almost the same. The structure of the polymers was characterized by FT-IR. NMR, and SEC. Good electroactivity of the copolymers was confirmed by UV and cyclic voltammetry (CV), and CV showed three pairs of redox peaks. The hyperbranched copolymers had a higher conductivity than the linear ones. It is suggested that the higher conductivity of the hyperbranched copolymer is due to the ordered distribution of peripheral EMAP segments that more easily form a conductive network. Therefore, the conductivity of the polymers is improved and controlled by the macromolecular architecture.

  • 16.
    Guo, Baolin
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Finne-Wistrand, Anna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Universal Two-Step Approach to Degradable and Electroactive Block Copolymers and Networks from Combined Ring-Opening Polymerization and Post-Functionalization via Oxidative Coupling Reactions2011In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 44, no 13, p. 5227-5236Article in journal (Refereed)
    Abstract [en]

    We present a universal strategy for the facile synthesis of degradable and electroactive block copolymers and organogels (DEBCGs) based on aniline oligomers and polyesters in a two-step approach, here exemplified by the preparation of a series of DECBCGs based on aniline tetramer (AT) and poly(e-caprolactone) (PCL). Polyesters with an aniline dimer (AD) segment were first obtained by controlled ring-opening polymerization (ROP) of e-caprolactone initiated by the amine group of AD with or without 2,2-bis(epsilon-caprolactone-4-yl) propane (BCP). The postpolymerization modification via an oxidative coupling reaction between AD and a polyester was then used to form the electroactive segment AT in the copolymers or organogels. The molecular weight and conductivity of the block copolymers and organogels were controlled by the AT content. The chemical structure, electroactivity, and thermal properties of DEBCGs were investigated by FT-IR, NMR, SEC, UV, cyclic voltammetry, TGA, and DSC. Our general strategy for the synthesis of DECBCGs avoids the multiple step reactions and low efficiency involved in previous work.

  • 17.
    Hakkarainen, Minna
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Adamus, Grazyna
    Centre of Polymer and Carbon Materials, Polish Academy of Sciences.
    Höglund, Anders
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Kowalczuk, Marek
    Centre of Polymer and Carbon Materials, Polish Academy of Sciences.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    ESI-MS reveals the influence of hydrophilicity and architecture on the water-soluble degradation product patterns of biodegradable homo- and copolyesters of 1,5-dioxepan-2-one and epsilon-caprolactone2008In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 41, no 10, p. 3547-3554Article in journal (Refereed)
    Abstract [en]

    The hydrolytic degradation process and degradation product patterns of biodegradable homo- and copolyesters of 1,5-dioxepan-2-one (DXO) and epsilon-caprolactone (CL) were monitored by electrospray ionization mass spectrometry (ESI-MS). The degradation product patterns were compared to mass loss, molecular weight changes, copolymer composition, and pH changes after various hydrolysis times. Water-soluble oligomers up to heptadecamer were identified after hydrolysis of hydrophilic PDXO, while only oligomers up to hexamer were detected after hydrolysis of the more hydrophobic PCL. The product pattern of DXO-CL-DXO triblock copolymer mainly consisted of DXO-based oligomers, whereas the CL/DXO multiblock copolymer degradation product pattern contained DXO and CL oligomers as well as oligomers containing both DXO and CL units. The DXO-rich oligomers, however, dominated the product patterns. ESI-MS gave valuable insights into the hydrolysis process of hydrophobic and hydrophilic polyesters and showed that hydrophilicity of the polymer as well as copolymer architecture both greatly influenced the water-soluble degradation product patterns.

  • 18.
    Hedfors, Cecilia
    et al.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Östmark, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Malmström, Eva E.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    Martinelle, Mats
    KTH, School of Biotechnology (BIO), Biochemistry.
    Thiol end-functionalization of poly(epsilon-caprolactone), catalyzed by Candida antarctica lipase B2005In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 38, no 3, p. 647-649Article in journal (Refereed)
    Abstract [en]

    The use of Candida antarctica Lipase B (CALB) chemoselective catalyst in the Thiol End-Functionalization of Poly(ε-caprolacetone) was discussed. Thiol-functionalization of poly(ε-caprolacetone)(PCL) was made by an initiation reaction catalyzed by CALB in bulk. 2-Mercaptoethanol (1) was used to initiate the enzyme-assisted ring opening polymerization of ε-caprolacetone(2) to give the desired thiol-functionalized polymer. The structure of the terminated PCL was confirmed by 13C nuclear magnetic resonance .

  • 19.
    Hua, Geng
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Franzén, Johan
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Organic chemistry.
    Odelius, Karin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Polymer Technology.
    Phosphazene-Catalyzed Regioselective Ring-Opening Polymerization of rac-1-Methyl Trimethylene Carbonate: Colder and Less is Better2019In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 52, no 7, p. 2681-2690Article in journal (Refereed)
    Abstract [en]

    The regioselective organocatalytic ring-opening polymerization (ROP) of a 6-membered cyclic carbonate, rac-1-methyl trimethylene carbonate, was studied using phosphazene base (t-BuP2) as the principle catalyst. The influence on the reaction kinetics caused by the reaction temperature (-74-60 degrees C), catalyst loading (0.5-2.5%), and reaction solvent (toluene and tetrahydrofuran) was systematically tuned and followed by H-1 NMR. All studied reactions reached close to or above 90% monomer conversion in 3 h, and all exhibited typical equilibrium polymerization behavior that is inherent to 6-membered cyclic carbonates. Good control over the molecular weight and distribution of the polycarbonate product was obtained in most studied conditions, with M-n ranging from similar to 4k to similar to 20k and D < 1.2. The regioregularity (X-reg) of the resulting polycarbonate was thoroughly studied using various NMR techniques, with the highest X-reg obtained being.0.90. The major influence from the reaction conditions on both the ROP kinetics and X-reg are as follows: higher reaction temperature resulted in a decrease of both; higher catalyst loading resulted in a faster ROP reaction but a slight decrease in X-reg; and toluene being a better solvent resulted in both faster reaction and higher X-reg. Throughout this study, we have demonstrated the possibility to synthesize regioregular aliphatic polycarbonate using an organic base as the ROP catalyst, contrary to the existing studies on similar systems where only metal-base catalysts were in focus and our systems showed similar high X-reg of the product.

  • 20.
    Iruthayaraj, Joseph
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Poptoshev, Evgeni
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Vareikis, Aušvydas
    Department of Polymer Chemistry, Vilnius University.
    Makuška, Ričardas
    Department of Polymer Chemistry, Vilnius University.
    van der Wal, Albert
    Lever Faberage Europe Global Technology Centre, Unilever R and D.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Adsorption of Low charge Density Polyelectrolyte Containing Poly(ethylene oxide) Side chains on Silica: Effects of Ionic strength and pH2005In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 38, no 14, p. 6152-6160Article in journal (Refereed)
    Abstract [en]

    Adsorption characteristics of a random copolymer of poly(ethylene oxide) monomethyl ether methacrylate and methacryloxyethyl trimethylammonium chloride (PEOMENIA:METAC) on silica were studied using stagnation point adsorption reflectometry (SPAR), quartz crystal microbalance with dissipation (QCM-D), and contact angle techniques. The PEOMEMA:METAC copolymer used in this study is a low charge density polyelectrolyte, with 2% of the monomer units carrying permanent positive charges and 98% containing poly(ethylene oxide) side chains that are approximately 45 repeating units long. The surface excess was determined as a function of pH and concentration of indifferent electrolyte. It was found that the presence of a small amount of 1: 1 electrolyte decreases the adsorbed amount significantly. Further, increasing the pH at a constant ionic strength, 10 mM, results in decreasing surface excess. It is suggested that the adsorption is realized via a combination of non-Coulomb interactions between the poly(ethylene oxide), PEO, grafts and protonated silanol groups at the silica-solution interface and an electrostatic interaction between the charged segments and the oppositely charged surface. Increasing pH and/or salt concentration results in progressive charging of the silica surface with the consequent decrease in affinity between silica and PEO, explaining the decrease in the adsorbed amount of the polymer.

  • 21. Karlsson, G. E.
    et al.
    Johansson, T. S.
    Gedde, Ulf W.
    KTH, Superseded Departments, Polymer Technology.
    Hedenqvist, Mikael S.
    KTH, Superseded Departments, Polymer Technology.
    Determining limonene diffusion in molten polyethylene from within 0.1 mu s molecular dynamics trajectories2002In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 35, no 19, p. 7453-7459Article in journal (Refereed)
    Abstract [en]

    Molecular dynamics simulations of the diffusion of limonene into molten polyethylene were performed in order to explore the possibility of using atomistic simulations to predict the diffusion of larger solute molecules in polymers. The system contained 6000 anisotropic united atom methylene units with a molar mass of 84 000 g mol(-1). A united atom limonene molecule (C10H16) was introduced into the polyethylene matrix. Limonene trajectories were generated for 2-100. ns at 77-227 degreesC. The simulated diffusivities were compared with experimental zero-concentration diffusivities of limonene in natural rubber and ultrahigh molar mass polyethylene, obtained from desorption measurements in the same temperature range. The simulated diffusivities and activation energy were within 30%. and 16% of the experimental thermodynamic diffusivities and activation energies, respectively. The simulated average diffusivities, obtained from 10 trajectories, changed by only 33% when the simulation time was shortened from 100 ns to 500 ps. The limonene molecule vibrated in a cagelike fashion on a 1-2 ps scale, whereas on a larger time scale the jumping was liquidlike. The limonene molecule showed tumbling during its motion through the polyethylene matrix.

  • 22.
    Karlsson, Sigbritt
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Dicarboxylic acids and ketoacids formed in degradable polyethylenes by zip depolymerisation through a cyclic transition state1997In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 30, p. 7721-7728Article in journal (Refereed)
    Abstract [en]

    The intermediate and final degradation products formed in six different low-density polyethylene (LDPE) films modified with either starch and/or pro-oxidants or photosensitizers (Scott-Gilead formulation [SG]) were investigated. We propose that dicarboxylic acids and ketoacids, formed in the materials to varying degrees, are due to both secondary oxidation products and a zip depolymerization mechanism by backbiting through a cyclic transition state. Hydrocarbons, ketones, carboxylic acids and dicarboxylic acids are formed during early stages of photo-oxidation, and the ketones disappeared while several ketoacids appeared and the relative amount of dicarboxylic acids increased in the most severely degraded materials. During prolonged photo-oxidation, additional oxidation of ketones and monocarboxylic acids to dicarboxylic acids explains the high amount of dicarboxylic acids. In the thermooxidized samples the amount of ketones and monocarboxylic acids remained high even in the most degraded samples. Mono-and dicarboxylic acids were formed in several micrograms per 100 mg of polymer, while the ketones and ketoacids were formed in fewer micrograms per 100 mg of polymer. LDPE modified with the iron dimethyldithiocarbamate (SG1) was the most susceptible material to photooxidation, while LDPE containing starch and pro-oxidants (LDPE-MB) was the most susceptible material to thermo-oxidation. Degraded LDPE-MB demonstrated less formation of degradation products; e.g., only in UV-initiated samples thermally degraded at 80 degrees C for 5 weeks could degradation products be detected. Larger amounts of ketones and ketoacids were formed in the SG materials than in the starch-filled materials.

  • 23.
    Koo, Jun Mo
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Kim, Hojun
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Lee, Minkyung
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Park, Seul-A
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Jeon, Hyeonyeol
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Shin, Sung-Ho
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Kim, Seon-Mi
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Cha, Hyun Gil
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Jegal, Jonggeon
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea..
    Kim, Byeong-Su
    Yonsei Univ, Dept Chem, Seoul 03722, South Korea..
    Choi, Bong Gill
    Kangwon Natl Univ, Dept Chem Engn, Samcheok 25913, Gangwon Do, South Korea..
    Hwang, Sung Yeon
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea.;UST, Adv Mat & Chem Engn, Daejeon 34113, South Korea..
    Oh, Dongyeop X.
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea.;UST, Adv Mat & Chem Engn, Daejeon 34113, South Korea..
    Park, Jeyoung
    KRICT, Res Ctr Biobased Chem, Ulsan 44429, South Korea.;UST, Adv Mat & Chem Engn, Daejeon 34113, South Korea..
    Nonstop Monomer-to-Aramid Nanofiber Synthesis with Remarkable Reinforcement Ability2019In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 52, no 3, p. 923-934Article in journal (Refereed)
    Abstract [en]

    Aramid nanofibers (ANFs), typically produced by exfoliating aramid microfibers (Kevlar) in alkaline media, exhibit excellent mechanical properties and have therefore attracted increased attention as nanoscale building blocks. However, the preparation of aramid microfibers involves laborious and hazardous processes, which limits the industrial-scale use of ANFs. This work describes a facile and direct monomer-to-ANF synthesis via an as-synthesized intermediate low-molecular-weight poly(p-phenylene terephthalamide) (PPTA) without requiring the environmentally destructive acids and high-order shearing processes. Under the employed conditions, PPTA immediately dissociates and self-assembles into ANFs within a time period of 15 h, which is much shorter than the time of 180 h (not including the Kevlar preparation time) required for the Kevlar-to-ANF conversion. Interestingly, the fabricated ANFs exhibit nanoscale dimensions and thermoplastic polyurethane (TPU) reinforcing effects similar to those of Kevlar-derived ANFs; i.e., a 1.5-fold TPU toughness improvement and a maximum ultimate tensile strength of 84 MPa are achieved at an ANF content of only 0.04 wt %. Remarkable reinforcement ability investigated by comprehensive analytical data comes from ANFs, which disturb ordered hydrogen bonding in hard segments and induce strain hardening along the elongation pathway. Thus, the developed approach paves the way to industrial-scale production of ANFs and related nanocomposites.

  • 24.
    Kozhuharov, Svilen
    et al.
    Univ Geneva, Dept Inorgan & Analyt Chem, Sci 2, 30 Quai Ernest Ansermet, CH-1205 Geneva, Switzerland..
    Radiom, Milad
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Surface and Corrosion Science. Univ Geneva, Dept Inorgan & Analyt Chem, Sci 2, 30 Quai Ernest Ansermet, CH-1205 Geneva, Switzerland..
    Maroni, Plinio
    Univ Geneva, Dept Inorgan & Analyt Chem, Sci 2, 30 Quai Ernest Ansermet, CH-1205 Geneva, Switzerland..
    Borkovec, Michal
    Univ Geneva, Dept Inorgan & Analyt Chem, Sci 2, 30 Quai Ernest Ansermet, CH-1205 Geneva, Switzerland..
    Persistence Length of Poly(vinyl amine): Quantitative Image Analysis versus Single Molecule Force Response2018In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 51, no 10, p. 3632-3639Article in journal (Refereed)
    Abstract [en]

    Single molecules of poly(vinyl amine) are analyzed in the adsorbed state by atomic force microscopy (AFM) in two different ways. First, high-resolution images of individual adsorbed polymers were recorded in monovalent electrolyte solutions. The backbone of the imaged polymers was digitized, and the directional correlation function and internal mean-square end-to-end distance were evaluated. These quantities were analyzed with the wormlike chain (WLC) model, and the persistence length was extracted. Second, individual polymer chains were picked up from the surface, and their force extension behavior was recorded in the same electrolyte solutions. These force profiles were also interpreted in terms of the WLC model, whereby the elastic contribution was also considered. Both techniques yield the persistence length of the polymer. From imaging one obtains a persistence length of about 1.6 nm, while the force experiments yield a value around 0.51 nm. We suspect that the force experiments reflect the intrinsic part of the persistence length, while the imaging experiments yield the persistence length including the electrostatic

  • 25.
    Lindqvist, Josefina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Nyström, Daniel
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hult, Anders
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Kinetic Study of the Surface-Initiated Atom Transfer Radical Polymerization from Bio-Fiber SurfacesIn: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835Article in journal (Refereed)
  • 26.
    Lindqvist, Josefina
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Nyström, Daniel
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Östmark, Emma
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Antoni, Per
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Johansson, Mats
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hult, Anders
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Dual-Responsive Bio-Fiber Surfaces via ATRPIn: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835Article in journal (Refereed)
  • 27.
    Linse, Per
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Physical Chemistry.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
    Modeling of Bottle-Brush Polymer Adsorption onto Mica and Silica Surfaces2009In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 42, no 16, p. 6310-6318Article in journal (Refereed)
    Abstract [en]

    The adsorption of a series of charged bottle-brush polymers with side chains of constant length on mica and silica surfaces is modeled using a lattice mean-field theory, and the predicted results are compared to corresponding experimental data. The bottle-brush polymers are modeled as being composed of two types of main-chain segments: charged segments and uncharged segments with an attached side chain. The composition variable X denotes the percentage of charged main-chain segments and ranges from X = 0 (uncharged bottle-brush polymer) to X = 100 (linear polyelectrolyte). The mica-like surface possesses a constant negative surface charge density and no special affinity, whereas the silica-like surface has a constant negative surface potential and a positive affinity for the side chains of the bottle-brush polymers. The model is able to reproduce a number of salient experimental features characterizing the adsorption of the bottle-brush polymers for the full range of the composition variable X on the two surfaces, and thereby quantifying the different nature of the two surfaces with respect to electrostatic properties and nonelectrostatic affinity for the polymer. In particular, the surface excess displays a maximum at X approximate to 50 for the mica surface and at X approximate to 10 for the silica surface. Moreover, the thickest adsorbed layer is obtained at X = 10-25.

  • 28. Linse, Per
    et al.
    Claesson, Per M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
    Modeling of Bottle-Brush Polymer Adsorption onto Mica and Silica Surfaces: Effect of Side-Chain Length2010In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 43, no 4, p. 2076-2083Article in journal (Refereed)
    Abstract [en]

    Adsorption of a series of charged bottle-brush polymers with side chains of different length on solid surfaces is modeled using a lattice mean-field theory. The bottle-brush polymers are modeled Lis being composed of two types of main-chain segments: charged segments and uncharged segments with ill attached side chain. The composition variable X denotes the percentage of charged main-chain segments and ranges from X = 0 (uncharged bottle-brush polymer) to X = 100 (linear polyelectrolyte). Two types of surfaces are considered: mica-like and silica-like. The mica-like surface possesses a constant negative surface charge density and no nonelectrostatic affinity for either main-chain or side-chain segments, whereas the silica-like Surface has a constant negative surface potential and a positive affinity for the side chains of the bottle-brush polymers. With the mica-like Surface. ill low X the surface excess becomes smaller and at X >= 25 it becomes larger with increasing side-chain length. Hence, the value of X at which the surface excess displays a maximum increases with the side-chain length. However, with the silica-like Surface the surface excess increases with increasing side-chain length at all X < 100, and the maximum of the surface excess appears at X approximate to 10 independent of the side-chain length.

  • 29.
    Magnusson, Helene
    et al.
    KTH, Superseded Departments, Polymer Technology.
    Malmström, Eva
    KTH, Superseded Departments, Polymer Technology.
    Hult, Anders
    KTH, Superseded Departments, Polymer Technology.
    Influence of reaction conditions on degree of branching in hyperbranched aliphatic polyethers from 3-ethyl-3-(hydroxymethyl)oxetane2001In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 34, no 17, p. 5786-5791Article in journal (Refereed)
    Abstract [en]

    The cationic ring-opening polymerization of 3-ethyl-3-(hydroxymethyl)oxetane to form hyperbranched polyethers has been studied. The polymerizations have been performed in bulk using sulfonium salt initiators. To produce polymers of different degrees of branching, the reaction conditions (reaction temperature and initiator) have been varied. Polymerizations have also been performed in the presence of a trifunctional core molecule, trimethylolpropane. The conversion of monomer turned out to be the main factor determining the degree of branching in the resulting polymer. Polymers with degrees of branching ranging from 0.15 to 0.41 were synthesized. When 3-ethyl-3-(hydroxymethyl)oxetane was polymerized by slow addition of monomer to a core molecule, a lower degree of branching was obtained compared to the one-step synthesis with full conversion of monomer. The polydispersity was generally slightly lower when a core molecule was used than in the one-step homopolymerization of 3-ethyl-3(hydroxymethyl)oxetane.

  • 30.
    Magnusson, Heléne
    et al.
    KTH, Superseded Departments, Polymer Technology.
    Malmström, Eva
    KTH, Superseded Departments, Polymer Technology.
    Hult, Anders
    KTH, Superseded Departments, Polymer Technology.
    Structure buildup in hyperbranched polymers from 2,2-bis(hydroxymethyl)propionic acid2000In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 33, no 8, p. 3099-3104Article in journal (Refereed)
    Abstract [en]

    The structure buildup in hyperbranched polyesters from 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) was studied experimentally. Bis-MPA and its dendritic trimer were both polymerized in bulk using acid catalyst. The fractions of terminal, dendritic, and linear repeating units were monitored by C-13 NMR during the course of reaction. Effect of slow monomer addition on the degree of branching in the final product was also studied. Hyperbranched polymers from bis-MPA with and without a core molecule were kept at the polymerization temperature in order to examine the effect of heat treatment on composition in the polymer. The fractions of the different repeating units were changing to a large extent with conversion. Slow monomer addition to a trifunctional core molecule gave a product with a degree of branching of 47%. Heat treatment of hyperbranched materials gave small changes in the fractions of the different repeating units in both materials and, eventually, gelling in the material without a core.

  • 31.
    Malkoch, Michael
    et al.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Carlmark, Anna
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Wodegiorgis, A
    Hult, Anders
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Malmström, Eva
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Dendronized aliphatic polymers by a combination of ATRP and divergent growth2004In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 37, no 2, p. 322-329Article in journal (Refereed)
    Abstract [en]

    Dendronized, hybrid dendritic-linear polymers were synthesized by either the "graft-onto" route or by atom transfer radical polymerization (ATRP) of macromonomers. In both ways, the main chain was composed of acrylate repeating units and the dendrons were based on the aliphatic ester skeleton obtained from 2,2-bis(methylol)propionic acid (bis-MPA). ATRP of macromonomers was not a viable route for monomers with side chains larger than second-generation dendrons, which is why a combination of the two approaches was required to obtain polymers with larger side chains. The "graft-onto" route was conducted by reacting hydroxyl groups on the main chain with the acetonide-protected 2,2-bis(hydroxymethyl)propionic anhydride. The acetonide protecting group was easily removed by treating a solution of the polymer with an acidic ion-exchange resin. Dendronized polymers with 1-3 generation dendron side groups were synthesized with a maximum molecular weight of ca. 86 kDa. The products were analyzed by H-1 and C-13 NMR, SEC, and MALDI-TOF.

  • 32. Malkoch, Michael
    et al.
    Schleicher, K.
    Drockenmuller, E.
    Hawker, C. J.
    Russell, T. P.
    Wu, P.
    Fokin, V. V.
    Structurally diverse dendritic libraries: A highly efficient functionalization approach using Click chemistry2005In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 38, no 9, p. 3663-3678Article in journal (Refereed)
    Abstract [en]

    The high fidelity and efficiency of Click chemistry are exploited in the synthesis of a library of chain end functionalized dendritic macromolecules. In this example, the selectivity of the Cu-catalyzed [3 + 2 pi] cycloaddition reaction of azides with terminal acetylenes, coupled with mild reaction conditions, permits unprecedented functional group tolerance during the derivatization of dendrimeric and hyperbranched scaffolds. The resulting dendritic libraries are structurally diverse, encompassing a variety of backbones/surface functional groups, and are prepared in almost quantitative yields under very mild conditions. The robust and simple nature of this procedure, combined with its applicability to many aspects of polymer synthesis and materials chemistry, demonstrates an evolving synergy between advanced organic chemistry and functional materials.

  • 33.
    Malkoch, Michel
    et al.
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Malmström, Eva
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Hult, Anders
    KTH, Superseded Departments, Fibre and Polymer Technology.
    Rapid and efficient synthesis of aliphatic ester dendrons and dendrimers2002In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 35, no 22, p. 8307-8314Article in journal (Refereed)
    Abstract [en]

    A divergent approach to synthesize dendritic aliphatic polyester structures based on 2,2-bis(hydroxymethyl) propionic acid (bis-MPA) is described. The key building block is the anhydride of isopropylidene-2,2-bis(methoxy) propionic acid which is synthesized in high yields through self-dehydration, utilizing N,N'-dicyclohexylcarbodiimide (DCC) as reagent. The high reactivity of the anhydride toward hydroxyl groups makes the divergent synthesis of dendrimers and dendrons viable. Dendritic growth occurs in the presence of protecting groups sensitive toward hydrogenolysis, such as benzyl esters and ethers. The acetonide-protecting group is easily removed under acidic conditions using DOWEX 50W-X2 resin in methanol. Fourth-generation dendrons and dendrimers were successfully synthesized in high yields utilizing 1.3-1.5 equiv of anhydride per hydroxyl group. Common characteristics of the esterification reaction were short reaction time, mild reaction conditions, easy monitoring by NMR analysis, and simple workup. This synthetic approach opens up the possibility to utilize orthogonal protecting groups of acetonide-protected 2,2-bis(hydroxymethyl) propionic anhydride as a novel building block.

  • 34.
    MALMSTROM, E
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    JOHANSSON, M
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    HULT, A
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    HYPERBRANCHED ALIPHATIC POLYESTERS1995In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 28, p. 1698-1703Article in journal (Refereed)
    Abstract [en]

    Hyperbranched, aliphatic polyesters of theoretically calculated molar masses 1200-44 300 were synthesized in the molten state from 2,2-bis(hydroxymethyl)propionic acid (repeating unit of AB(x) type) and 2-ethyl-2-(hydroxymethyl)-1,3-propanediol (core molecule) using acid catalysis. The synthesis procedure was a pseudo-one-step reaction where stoichiometric amounts corresponding to each generation were added successively. The resulting polymers were glassy, slightly yellow solids at room temperature with hydroxyl groups as terminal groups. The degree of branching of the polyesters was determined with the help of model compounds using C-13-NMR and was found to be near 80%. The material exhibited good thermal stability as analyzed with TGA in a nitrogen atmosphere. Glass transition temperatures were determined using DSC and were found to be about 40 degrees C and to be relatively insensitive to variations in molar mass.

  • 35.
    Medina, Lilian
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Biocomposites. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center.
    Nishiyama, Yoshiharu
    Univ. Grenoble Alpes, CNRS,CERMAV, 38000 Grenoble, France.
    Daicho, Kazuho
    University of Tokyo, Japan.
    Saito, Tsuguyuki
    University of Tokyo, Japan.
    Yan, Min
    KTH, School of Engineering Sciences (SCI).
    Berglund, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Nanostructure and Properties of Nacre-Inspired Clay/Cellulose Nanocomposites—Synchrotron X-ray Scattering Analysis2019In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 52, no 8, p. 3131-3140Article in journal (Refereed)
    Abstract [en]

    Nacre-inspired clay nanocomposites have excellent mechanical properties, combined with optical transmittance, gas barrier properties, and fire retardancy, but the mechanical properties are still below predictions from composite micromechanics. The properties of montmorillonite clay/nanocellulose nanocomposite hybrids are investigated as a function of clay content and show a maximum Young’s modulus as high as 28 GPa. Ultimate strength, however, decreases from 280 to 125 MPa between 0 and 80 wt % clay. Small-angle and wide-angle X-ray scattering data from synchrotron radiation are analyzed to suggest nanostructural and phase interaction factors responsible for these observations. Parameters discussed include effective platelet modulus, platelet out-of-plane orientation distribution, nanoporosity, and platelet agglomeration state.

  • 36.
    Mittal, Nitesh
    KTH, School of Engineering Sciences (SCI), Mechanics, Fluid Physics. KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Centres, Wallenberg Wood Science Center. KTH Royal Institute of Technology.
    Water-Induced Structural Rearrangements on the Nanoscale in Ultrathin Nanocellulose Films2019In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835Article in journal (Refereed)
  • 37.
    Montanez, Maria I.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Campos, Luis M.
    Antoni, Per
    Hed, Yvonne
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Walter, Marie Valerié
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Krull, Brandon T.
    Khan, Anzar
    Hult, Anders
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Hawker, Craig J.
    Malkoch, Michael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
    Accelerated Growth of Dendrimers via Thiol-Ene and Esterification Reactions2010In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 43, no 14, p. 6004-6013Article in journal (Refereed)
    Abstract [en]

    By taking advantage of the orthogonal nature of thiol-ene coupling and anhydride based esterification reactions, a facile and chemoselective strategy to dendritic macromolecules has been developed The ability to interchange growth steps based on thiol-ene and anhydride chemistry allows the synthesis of fifth-generation dendrimers in only five steps and under benign reaction conditions In addition, the presented coupling chemistries eliminate the traditional need for protection/deprotection steps and afford dendrimers in high yield and purity The modularity of this strategy coupled with the latent reactivity of the alkene/hydroxyl chain ends was demonstrated by using different cores (alkene and hydroxyl functional), various AB(2) and CD2 monomers and a range of chain end groups As a result, three dendritic libraries were prepared which exhibited tunability of both the chemical functionality and physical properties including the fabrication of PEG hydrogels.

  • 38.
    Moyassari, Ali
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Gkourmpis, Thomas
    Borealis AB, Innovat & Technol, SE-44486 Stenungsund, Sweden..
    Hedenqvist, Mikael S.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Gedde, Ulf W.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Molecular Dynamics Simulations of Short-Chain Branched Bimodal Polyethylene: Topological Characteristics and Mechanical Behavior2019In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 52, no 3, p. 807-818Article in journal (Refereed)
    Abstract [en]

    It has previously been shown that polyethylene (PE) with a bimodal molar mass distribution has a high fracture toughness. Our approach has been to use coarse-grained (CG) molecular dynamics (MD) simulations to investigate the effects of including short-chain branches in the high molar mass fraction of bimodal PE on topological features and mechanical behavior of the material. The CG potentials were derived, validated, and utilized to simulate melt equilibration, cooling, crystallization, and mechanical deformation. Crystallinity, tie chain, and entanglement concentrations were continuously monitored. During crystallization, the branched bimodal systems disentangled to a lesser degree and ended up with a higher entanglement density than the linear bimodal systems simulated in our previous study. The increase in entanglement concentration was proportional to the content of the branched high molar mass fraction. A significantly higher tie chain concentration was obtained in the short-chain branched bimodal systems than in the linear systems. The increase in the number of ties was more pronounced than the increase in the number of entanglements. The tie chain concentration was not proportional to the content of the high molar mass fraction. Despite a lower crystal thickness and content, the elastic modulus and yield stress values were higher in the branched bimodal systems. A more pronounced strain hardening region was observed in the branched systems. It was suggested that the higher tie chain and entanglement concentration prior to the deformation, the more extensive disentanglement during the deformation, and the disappearance of formed voids prior to failure point were the reasons for the observed higher toughness of the short-chain branched bimodal PE compared with that of the linear bimodal systems. The toughest system, which contained respectively 25 and 75 wt % low molar mass and branched high molar mass fractions, had the highest tie chain concentration and the second highest entanglement concentration of the simulated systems.

  • 39.
    Nilsson, Camilla
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Johansson, Mats K. G.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Malmström, Eva E.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Synthesis and Physical and Rheological Characterization of Aliphatic Polyester Dendrimers with Different Core Structures2008In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835Article in journal (Other academic)
  • 40.
    Nyström, Andreas
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Malkoch, Michael
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Furo, Istvan
    KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Nyström, Daniel
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Unal, Kerem
    Antoni, Per
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Vamvounis, George
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hawker, Craig
    Wooley, Karen
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Hult, Anders
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Characterization of Poly(norbornene) Dendronized Polymers Prepared by Ring-Opening Metathesis Polymerization of Dendron Bearing Monomers2006In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 39, no 21, p. 7241-7249Article in journal (Refereed)
    Abstract [en]

    The preparation and characterization of a series of first to fourth generation dendronized poly-(norbornene)s are presented. The monomers were synthesized in a divergent fashion from 5-norbornene-2-methanol, utilizing the acetonide protected anhydride of 2,2-bis(methylol)propionic acid. The norbornenyl bearing dendrons were polymerized by ring-opening metathesis polymerization, and it was found that the Grubbs' first generation catalyst resulted in polymers with lower polydispersity compared to the materials obtained when employing the second generation catalyst. Two series of first to fourth generation polymers were characterized by DSC, SEC, and dynamic rheological measurements. In addition, it was found that the fourth generation material could form regular, porous membranes and birefringent fibers. The membranes were characterized with atomic force and optical microscopy. The birefringent fibers were analyzed with X-ray diffraction, polarized FTIR, and polarized optical microscopy.

  • 41.
    Olsen, Peter
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Odelius, Karin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Keul, Helmut
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Macromolecular Design via an Organocatalytic, Monomer-Specific and Temperature-Dependent "On/Off Switch": High Precision Synthesis of Polyester/Polycarbonate Multiblock Copolymers2015In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 48, no 6, p. 1703-1710Article in journal (Refereed)
    Abstract [en]

    The employment of a monomer-specific on/off switch was used to synthesize a nine-block copolymer with a predetermined molecular weight and narrow distribution (D = 1.26) in only 2.5 h. The monomers consisted of a six-membered cyclic carbonate (i.e., 2-allyloxymethyl-2-ethyl-trimethylene carbonate (AOMEC)) and epsilon-caprolactone (epsilon CL), which were catalyzed by 1,5,7-triazabicyclo[4.4.0]-dec-5-ene (TBD). The dependence of polymerization rate with temperature was different for the two monomers. Under similar reaction conditions, the ratio of the apparent rate constant of AOMEC and epsilon CL [k(p)(app)(AOMEC)/k(p)(app)(epsilon CL)] changes from 400 at T = -40 degrees C to 50 at T = 30 degrees C and 10 at T = 100 degrees C. Therefore, by decreasing the copolymerization temperature from 30 degrees C to -40 degrees C, the conversion of epsilon CL can be switched off, and by increasing the temperature to 30 degrees C, the conversion of epsilon CL can be switched on again. The addition of AOMEC at T = -40 degrees C results in the formation of a pure carbonate block. The cyclic addition of AOMEC to a solution of epsilon CL along with a simultaneous temperature change leads to the formation of multiblock copolymers. This result provides a new straightforward synthetic route to degradable multiblock copolymers, yielding new interesting materials with endless structural possibilities.

  • 42.
    Olsson, Richard T.
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Krämer, Roland
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Lopez-Rubio, Amparo
    Torres-Giner, Sergio
    Jose Ocio, Maria
    Maria Lagaron, Jose
    Extraction of Microfibrils from Bacterial Cellulose Networks for Electrospinning of Anisotropic Biohybrid Fiber Yarns2010In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 43, no 9, p. 4201-4209Article in journal (Refereed)
    Abstract [en]

    Electrospinning of uniform biohybrid fibers with concealed cellulose microfibrils (CMF) is reported as a promising and environmentally sound concept for reinforcement of polymer nonwoven fiber systems of fine dimensions. The extraction and refinement of the high-strength crystalline microfibril bundles (15-20 nm thick) from bacterial cellulose networks is presented, as well as their morphology prior to and post electrospinning. Nanofibers composed of a poly(methyl methacrylate) (PMMA) matrix with cellulose contents reaching 20 wt % were repeatedly obtained. A high deuce of dispersion of the microfibrils was obtained for a variety of CMF contents and the aggregation of the CMF was greatly suppressed as the microfibrils were aligned and rapidly sealed inside the acrylate matrix during the continuous formation of the fibers. The limited CMF aggregation up to 7 wt % was related to a suppressed phase separation caused by the rapid solidification of the polymer solutions during spinning. The fibers' diameters decreased significantly from similar to 1.8 mu m (1 wt %) to similar to 100 nm (20 wt %) with increasing cellulose contents, resulting in CMF agglomerations and percolating architectures within the acrylate host, which was consistent with microscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) evaluations. The nominal content of cellulose in the fibers was assessed by Lorentzian profile fit assignment of the crystalline vs amorphous fractions of the fibers' X-ray diffractograms. TGA of fibers with low CMF content revealed that both CMF and PMMA showed a significantly improved thermal stability in the composite material. The biohybrid fibers were continuously aligned into an anisotropic nanocomposite yarns from a liquid support during spinning. The strategy described herein may allow for new mechanically robust nonwoven fiber systems, or be used as implemented on existing electrospun formulations that are lacking mechanical integrity. It is envisioned that the cellulose microfibrils may be of importance in biomedical applications where biocompatibility is a requirement.

  • 43.
    Olsén, Peter
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Odelius, Karin
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Polymer Technology.
    Ring-Closing Depolymerization: A Powerful Tool for Synthesizing the Allyloxy-Functionalized Six-Membered Aliphatic Carbonate Monomer 2-Allyloxymethyl-2-ethyltrimethylene Carbonate2014In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 47, no 18, p. 6189-6195Article in journal (Refereed)
    Abstract [en]

    Ring-dosing depolymerization is demonstrated to be a powerful synthetic methodology for the formation of six-membered functional aliphatic carbonate monomers, providing a rapid, straightforward, inexpensive, and green route for obtaining six-membered functional aliphatic carbonate monomers at a scale greater than 100g. The utility of this technique was observed via the synthesis of the allyloxy-functionalized six-membered cyclic carbonate monomer 2-allyloxymethyl-2-ethyltrimethylene carbonate (AOMEC). The synthesis was performed in a one-pot bulk reaction, starting from trimethylolpropane allyl ether, diethyl carbonate, and NaH, resulting in a final AOMEC yield of 63%. The synthetic methodology is based upon the reversible nature of this class of polymers. The anionic environment produced by NaH was observed to mediate the monomer equilibrium concentration; thus, an additional catalyst is not required to induce depolymerization. 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD) was demonstrated to be a very active catalyst for the ring-opening polymerization (ROP) of AOMEC, resulting in a rapid (k(p)(aPP) =28.2 s(-1)) and controlled polymerization with a low dispersity D = 1.2). The availability and activity of the functionality of poly(AOMEC)s were established through subsequent postpolymerization functionalization via the UV-initiated thiol-ene chemistry of poly(AOMEC) with 1-dodecanethiol and benzophenone as a radical initiator. The functionalization proceeded with high control and with a linear relation between the molecular weight and conversion of the unsaturation, revealing the high orthogonality of the reaction and the stability of the carbonate backbone. Hence, as a synthetic methodology, depolymerization provides a straightforward and simple approach for the synthesis of the highly versatile functional carbonate AOMEC. In addition, formation of the monomer does not require any solvents, reactive ring-dosing reagents, or transition-metal-based depolymerization catalysts, thereby providing a "greener" route for obtaining functional carbonate monomers and polymers.

  • 44.
    Pei, Aihua
    et al.
    KTH, School of Biotechnology (BIO).
    Malho, Jani-Markus
    Ruokolainen, Janne
    Zhou, Qi
    KTH, School of Biotechnology (BIO), Glycoscience.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Strong Nanocomposite Reinforcement Effects in Polyurethane Elastomer with Low Volume Fraction of Cellulose Nanocrystals2011In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 44, no 11, p. 4422-4427Article in journal (Refereed)
    Abstract [en]

    Polyurethane/cellulose nanocrystal nanocomposites with ultrahigh tensile strength and stain-to-failure with strongly improved modulus were prepared by adding cellulose nanocrystals (CNCs) during the preparation of prepolymer. The nanostructure of this polyurethane consisted of individualized nanocellulose crystals covalently bonded and specifically associated with the hard polyurethane (PU) microdomains as characterized by Fourier transform infrared spectroscopy and transmission electron microscopy. The storage modulus and thermal stability of the nanocomposites were significantly improved as measured by dynamic mechanical analysis. This was due to a combination of CNCs reinforcement in the soft matrix and increased effective cross-link density of the elastomer network due to CNC-PU molecular interaction. Tensile test revealed that the nanocomposites have both higher tensile strength and strain-to-failure. In particular, with only 1 wt % of cellulose nanocrystals incorporated, an 8-fold increase in tensile strength and 1.3-fold increase in strain-to-failure were achieved, respectively. Such high strength indicates that CNCs orient strongly at high strains and may also induce synergistic PU orientation effects contributing to the dramatic strength enhancement. The present elastomer nanocomposite outperforms conventional rubbery materials and polyurethane nanocomposites reinforced with microcrystalline cellulose, carbon nanotubes, or nanoclays.

  • 45.
    Pronoitis, Charalampos
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Hua, Geng
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Hakkarainen, Minna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Odelius, Karin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology.
    Biobased Polyamide Thermosets: From a Facile One-Step Synthesis to Strong and Flexible Materials2019In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 52, no 16, p. 6181-6191Article in journal (Refereed)
    Abstract [en]

    Biobased polyamide (PA) thermosets composed of renewable ethylene brassylate were synthesized through a one-step reaction under solvent-free conditions, at 100 degrees C in the presence of an organocatalyst. Under these conditions, thermoset formation times as low as 10 min were achieved. The thermosets were easily prepared as thin, transparent films with high strength, flexibility, and high thermal stability. The ester-to-amine content and formation of ethylene glycol in situ as a byproduct of the reaction were studied and correlated with the final properties of the materials. Crystalline oligoester segments were identified as a result of ring-opening polymerization and were shown to have a beneficial effect on the mechanical properties of the thermosets and endowed shape-memory behavior. In contrast to other routes, employing multistep monomer preparation, harsh conditions, and chlorinated reagents, this procedure contributed to the development of sustainable, functional PA thermosets.

  • 46. Ryner, M.
    et al.
    Stridsberg, K.
    Albertsson, Ann-Christine
    KTH, Superseded Departments, Polymer Technology.
    von Schenck, H.
    Svensson, M.
    Mechanism of ring-opening polymerization of 1,5-dioxepan-2-one and L-lactide with stannous 2-ethylhexanoate. A theoretical study2001In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 34, no 12, p. 3877-3881Article in journal (Refereed)
    Abstract [en]

    A theoretical study of the ring-opening polymerization (ROP) mechanism of 1,5-dioxepana-2-one (DXO) and (L)-lactide (LLA) with stannous(IE) a-ethylhexanoate (Sn(Oct)(2)) is presented. The B3LYP density functional method has been used for the quantum chemical calculations. Our results support a coordination-insertion mechanism initiated by a tin-alkoxide species formed prior to the ROP. The rate-determining step in the ROP was the nucleophilic attack of the alkoxide on the carbonyl carbon of the monomer. The activation energy for the ROP of DXO with Sn(Oct ')(2) has been determined to be 19.8 kcal/mol and for L-lactide 20.6 kcal/mol. At normal reaction temperatures, a ligand may dissociate as Oct 'H during propagation. An excess of carboxylic acid hinders the coordination of monomer to the initiating/propagating complex.

  • 47. Ryner, Maria
    et al.
    Finne, Anna
    KTH, Superseded Departments, Polymer Technology.
    Albertsson, Ann-Christine
    KTH, Superseded Departments, Polymer Technology.
    Kricheldorf, Hans R.
    L-lactide macromonomer synthesis initiated by new cyclic tin alkoxides functionalized for brushlike structures2001In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 34, no 21, p. 7281-7287Article in journal (Refereed)
    Abstract [en]

    L-Lactide macromonomers with an incorporated double bond were successfully synthesized by controlled ring-opening polymerization initiated by two new cyclic tin alkoxides (1,1-di-n-butyl-stanna-2,7-dioxacyclo-4-heptene and 9,9,20,20-tetrabutyl-8,10,19,21-tetraoxa-9,20-distanna-dispiro[5.5.5.5]d ocosa-2,14-diene). Initiators and crude reaction mixtures were characterized by NMR. H-1 NMR analysis showed that the initiators were completely reacted in the polymerization and that both tin-oxygen bonds were reactive and participated in propagation. The polymerizations were performed in chloroform at 60 degreesC, and the molecular weight was effectively controlled by adjusting the monomer-to-initiator ratio. The molecular weight distribution was narrow (<1.1) for both high and low molecular weights (3000-72 000 g/mol). A plot of M-n vs conversion was linear up to a conversion of 98%, showing a system propagating in a controlled manner. The kinetic investigation showed that all of the polymerizations were first order in monomer and that no termination reactions occurred during polymerization.

  • 48. Selegard, Robert
    et al.
    Rouhbalchsh, Zeinab
    Shirani, Hamid
    Johanson, Leif B. G.
    Norman, Patrick
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Linares, Mathieu
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Aili, Daniel
    Nilsson, K. Peter R.
    Distinct Electrostatic Interactions Govern the Chiro-Optical Properties and Architectural Arrangement of Peptide-Oligothiophene Hybrid Materials2017In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 50, no 18, p. 7102-7110Article in journal (Refereed)
    Abstract [en]

    The development of chiral optoelectronic materials is of great interest due to their potential of being utilized in electronic devices, biosensors, and artificial enzymes. Herein, we report the chiral optical properties and architectural arrangement of optoelectronic materials generated from noncovalent self-assembly of a cationic synthetic peptide and five chemically defined anionic pentameric oligothiophenes. The peptide-oligothiophene hybrid materials exhibit a three-dimensional ordered helical structure and optical activity in the pi-pi* transition region that are observed due to a single chain induced chirality of the conjugated thiophene backbone upon interaction with the peptide. The latter property is highly dependent on electrostatic interactions between the peptide and the oligothiophene, verifying that a distinct spacing of the carboxyl groups along the thiophene backbone is a major chemical determinant for having a hybrid material with distinct optoelectronic properties. The necessity of the electrostatic interaction between specific carboxyl functionalities along the thiophene backbone and the lysine residues of the peptide, as well as the induced circular dichroism of the thiophene backbone, was also confirmed by theoretical calculations. We foresee that our findings will aid in designing optoelectronic materials with dynamic architectonical precisions as well as offer the possibility to create the next generation of materials for organic electronics and organic bioelectronics.

  • 49.
    Simpson, Neil
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Takwa, Mohamad
    KTH, School of Biotechnology (BIO), Biochemistry.
    Hult, Karl
    KTH, School of Biotechnology (BIO), Biochemistry.
    Johansson, Mats K. G.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Martinelle, Mats
    KTH, School of Biotechnology (BIO), Biochemistry.
    Malmström, Eva
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Thiol-functionalized poly(omega-pentadecalactone) telechelics for semicrystalline polymer networks2008In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 41, no 10, p. 3613-3619Article in journal (Refereed)
    Abstract [en]

    Semicrystalline macromonomers based on poly(pentadecalactone), PPDL, have been synthesized by the lipase-catalyzed ring-opening of the otherwise chemically inert pentadecalactone monomer. The macromonomers were designed to have reactive thiols as end groups by the appropriate choice of initiator and chain terminator. The thiol functional macromonomers were then used together with ene monomers to give crosslinked thin films after irradiation in the molten state by UV light in the presence of a photoinitiator (Irgacure 65 1). Two different ene monomers were used, i.e., a tetrafunctional norbornene species and a trifunctional allyl ether maleate species, and resulted in semicrystalline cured films when cured with PPDL. An amorphous, commercially available, trifunctional thiol, trimethylolpropane tri(3-mercaptopropionate), TRIS, was also used for network formation in order to better understand the effect of crystallinity. All thiol-ene systems were found to be readily photopolymerised to high conversion. The PPDL-based networks were semicrystalline in the crosslinked state where the degree of crystallinity was found to depend on the nature of the cross-linker. Networks based on TRIS were found to be amorphous.

  • 50.
    Srivastava, Rajiv
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Albertsson, Ann-Christine
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Enzyme-Catalyzed Ring-Opening Polymerization of Seven-Membered Ring Lactones Leading to Terminal-Functionalized and Triblock Polyesters2006In: Macromolecules, ISSN 0024-9297, E-ISSN 1520-5835, Vol. 39, no 1, p. 46-54Article in journal (Refereed)
    Abstract [en]

    Terminal-functionalized polyesters and triblock polyesters were synthesized by lipase-CA-catalyzed ring-opening polymerization of seven-membered ring lactones, i.e., 1,5-dioxepan-2-one (DXO) and epsilon-caprolactone (CL), in the bulk in the presence of an appropriate alcohol that acts as an initiator. To introduce a double bond at the chain end, 4-pentene-2-ol was used to initiate the polymerization of the lactones. The unsaturation introduced at the chain end in this way is a useful approach for synthesizing comb polymers. Two different dihydroxyl compounds, viz. poly(caprolactone diol) and poly(ethylene glycol), were used as macro-initiators. Triblock copolymers were synthesized in this way, where the macro-initiator formed the middle block. Polymers having different degrees of polymerization were synthesized by varying the molar feed ratio of monomer to initiator. DXO and CL showed significant differences in reactivity toward lipase-CA-catalyzed polymerization initiated by different alcohols as initiators. The polymers were characterized by FTIR, NMR, SEC, optical microscopy, and DSC techniques.

12 1 - 50 of 63
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