Global ETD Search

1	Maßgeschneiderte azobenzolhaltige Polymere für Untersuchungen zum photoinduzierten Massetransport Börger, Volker. Unknown Date (has links) (PDF) Techn. Universiẗat, Diss., 2004--Braunschweig.
2	Kontrollierte Darstellung von Blockcopolymeren durch Atom transfer radical polymerization (ATRP) und Untersuchungen der Oberflächenmorphologie durch Rasterkraftmikroskopie Reining, Birte. Unknown Date (has links) (PDF) Techn. Hochsch., Diss., 2000--Aachen.
3	Aufbau definierter Polymerarchitekturen durch radikalische Polymerisation unter Atomtransfer (ATRP) Wittmann, Gabriele. Unknown Date (has links) Techn. Universiẗat, Diss., 2003--Darmstadt.
4	Darstellung von Telechelen auf Acrylat- und Methacrylatbasis durch "atom transfer radical polymerisation" und "atom transfer radical addition" Pilgram, Peter. Unknown Date (has links) (PDF) Techn. Hochsch., Diss., 2002--Aachen.
5	Synthesis and controlled radical polymerization of multifunctional monomers / Synthese und kontrollierte radikalische Polymerisation multifunktioneller Monomere Yin, Meizhen 30 June 2004 (has links) (PDF) Multifunctional monomers on the basis of acryl- and methacryl derivatives were synthesized and different protective groups were used. After polymerization the protective groups were removed by different methods. Various initiators for the NMP of the monomers were synthesized and the reaction conditions were optimized. The results showed that NMP was not a suitable method for multifunctional acryl- and methacryl derivatives to achieve well-defined homopolymers, although it was successful for control of polymerization of styrene and block copolymerization of multifunctional acryl- and methacryl derivatives with alkoxyamine terminated polystyrene. The ATRP of multifunctional acrylates and methacrylates has been successfully performed, as well as the block copolymerization of multifunctional acrylates and methacrylates. Relatively low polydispersities of the corresponding polymers (PD=1.18-1.36) and reasonably high rates of polymerization could be achieved when Me6TREN and PMDETA were used as ligands. However, the ATRP of multifunctional acrylamides and methacrylamides failed. The RAFT-polymerization of styrene, acrylamide and acrylate using BDTB as a CTA and AIBN as an initiator afforded polymers with narrow molecular weight distribution (PD=1.13-1.26). A kinetic investigation and the further synthesis of block copolymers using dithioester-terminated homopolymers as macroCTAs showed that the RAFT polymerization of acrylamide M9b proceeded in a living manner. However, BDTB does not control the reaction of methacrylic monomers, such as methacrylates and methacrylamides. The bulk phase behavior of the block copolymers were examined by means of DSC and the surface behaviors of block copolymers as thin layers were examined with AFM. Two-phase transitions in the block copolymers were observed clearly by DSC, indicative of the appearance of phase separations, which were seen in an AFM image. In conclusion, multifunctional acryl- and methacryl derivatives failed to achieve well-defined homopolymers by NMP. However, this method was successful for block copolymerization of multifunctional acryl- and methacryl derivatives with alkoxyamine terminated polystyrene. Multifunctional acrylates and methacrylates were successfully homopolymerized and block copolymerized by ATRP. Multifunctional acrylates and acrylamides were suitable for homopolymerization and block copolymerization by the RAFT process. Thus far, it is difficult to homopolymerize multifunctional methacrylamides in controlled way. ATRP Nitroxide RAFT multifunktionelle Monomere ATRP RAFT controlled radical polymerization multifunctional monomer nitroxide ddc:540 rvk:VK 8007 Atom-Transfer-Polymerisation Funktionelle Monomere Nitroxylradikal Radikalische Polymerisation
6	Synthesis and characterization of stimuli-responsive microgels based on poly(glycidol)block copolymers / Synthese und Charakterisierung von stimuli-sensitiven Mikrogelen basierend auf Polyglycidol-Blockcopolymeren Mendrek, Sebastian 24 April 2006 (has links) (PDF) New water soluble, attainable to ATRP polymerization Cl-terminated poly(glycidol) macroinitiators were prepared by modification of (Omega)-hydroxyl group of poly(glycidol acetal) using 2-chloropropionyl chloride fallowed by selective acidic deprotection of acetal groups. The obtained macroinitiators of different molar masses were successfully employed in ATRP of NIPAM and 4VP to give well-defined stimuli sensitive block copolymers of targeted molar ratio of blocks. The results obtained from light scattering methods showed formation of stable aggregates upon stimuli (pH or temperature) by all the obtained polymers. Additionally, photocrosslinkable block copolymers of glycidol and NIPAM having incorporated moieties of chromophore (2-(dimethyl maleinimido)-N-ethyl-acryl amide) were prepared using macroinitiator technique and used to synthesis of temperature sensitive microgels. Conjunction points have been successfully formed by UV irradiation of polymer water solution above cloud point. The influence of such parameters like block ratio, block length, amount of chromophore, concentration, irradiation time, temperature and heating rate on the properties of obtained microgels was investigated. The obtained core-shell structures were stable under critical conditions and showed continuous volume phase separation process upon increase of temperature, fully reversible and reproducible (no hysteresis effect). Thus, the proposed method not only gave the opportunity to control size or swelling degree of microgels, but also diminished gradient in crosslinking density (random chromophore distribution in polymer backbone), improved colloid stability (poly(glycidol) shell) and completely eliminated additives (surfactants, initiators, stabilizers). ATRP Anionische Polymerisation Blockcopolymere Makroinitiator stimuli-sensitiv ATRP Anionic Polymerisation Macroinitiator block copolymers stimuli-sensitive ddc:540 rvk:VK 8007 Anionische Polymerisation Atom-Transfer-Polymerisation Blockcopolymere Initiator &lt;Chemie&gt; Mikrogel
7	Synthesis and characterization of stimuli-responsive microgels based on poly(glycidol)block copolymers Mendrek, Sebastian 05 April 2006 (has links) New water soluble, attainable to ATRP polymerization Cl-terminated poly(glycidol) macroinitiators were prepared by modification of (Omega)-hydroxyl group of poly(glycidol acetal) using 2-chloropropionyl chloride fallowed by selective acidic deprotection of acetal groups. The obtained macroinitiators of different molar masses were successfully employed in ATRP of NIPAM and 4VP to give well-defined stimuli sensitive block copolymers of targeted molar ratio of blocks. The results obtained from light scattering methods showed formation of stable aggregates upon stimuli (pH or temperature) by all the obtained polymers. Additionally, photocrosslinkable block copolymers of glycidol and NIPAM having incorporated moieties of chromophore (2-(dimethyl maleinimido)-N-ethyl-acryl amide) were prepared using macroinitiator technique and used to synthesis of temperature sensitive microgels. Conjunction points have been successfully formed by UV irradiation of polymer water solution above cloud point. The influence of such parameters like block ratio, block length, amount of chromophore, concentration, irradiation time, temperature and heating rate on the properties of obtained microgels was investigated. The obtained core-shell structures were stable under critical conditions and showed continuous volume phase separation process upon increase of temperature, fully reversible and reproducible (no hysteresis effect). Thus, the proposed method not only gave the opportunity to control size or swelling degree of microgels, but also diminished gradient in crosslinking density (random chromophore distribution in polymer backbone), improved colloid stability (poly(glycidol) shell) and completely eliminated additives (surfactants, initiators, stabilizers). info:eu-repo/classification/ddc/540 ddc:540
8	Synthesis and controlled radical polymerization of multifunctional monomers Yin, Meizhen 08 June 2004 (has links) Multifunctional monomers on the basis of acryl- and methacryl derivatives were synthesized and different protective groups were used. After polymerization the protective groups were removed by different methods. Various initiators for the NMP of the monomers were synthesized and the reaction conditions were optimized. The results showed that NMP was not a suitable method for multifunctional acryl- and methacryl derivatives to achieve well-defined homopolymers, although it was successful for control of polymerization of styrene and block copolymerization of multifunctional acryl- and methacryl derivatives with alkoxyamine terminated polystyrene. The ATRP of multifunctional acrylates and methacrylates has been successfully performed, as well as the block copolymerization of multifunctional acrylates and methacrylates. Relatively low polydispersities of the corresponding polymers (PD=1.18-1.36) and reasonably high rates of polymerization could be achieved when Me6TREN and PMDETA were used as ligands. However, the ATRP of multifunctional acrylamides and methacrylamides failed. The RAFT-polymerization of styrene, acrylamide and acrylate using BDTB as a CTA and AIBN as an initiator afforded polymers with narrow molecular weight distribution (PD=1.13-1.26). A kinetic investigation and the further synthesis of block copolymers using dithioester-terminated homopolymers as macroCTAs showed that the RAFT polymerization of acrylamide M9b proceeded in a living manner. However, BDTB does not control the reaction of methacrylic monomers, such as methacrylates and methacrylamides. The bulk phase behavior of the block copolymers were examined by means of DSC and the surface behaviors of block copolymers as thin layers were examined with AFM. Two-phase transitions in the block copolymers were observed clearly by DSC, indicative of the appearance of phase separations, which were seen in an AFM image. In conclusion, multifunctional acryl- and methacryl derivatives failed to achieve well-defined homopolymers by NMP. However, this method was successful for block copolymerization of multifunctional acryl- and methacryl derivatives with alkoxyamine terminated polystyrene. Multifunctional acrylates and methacrylates were successfully homopolymerized and block copolymerized by ATRP. Multifunctional acrylates and acrylamides were suitable for homopolymerization and block copolymerization by the RAFT process. Thus far, it is difficult to homopolymerize multifunctional methacrylamides in controlled way. info:eu-repo/classification/ddc/540 ddc:540
9	Blending of Proton Conducting Copolymers Weißbach, Thomas 20 October 2010 (has links) (PDF) Highly proton conducting polymers for operation in hydrogen/oxygen proton exchange membrane fuel cells (PEMFCs) provide often a poor mechanical strength due to high water contents. To strengthen the conducting polymers, blends with different ratios of partially fluorinated sulfonic acid graft and diblock copolymers with perfluorinated polymers were prepared. To analyze the effect of the different quantities of the compounds, with regard to water sorption and proton conducting properties, membranes were prepared by dissolving the components and drop casting. Partially sulfonated poly([vinylidene difluoride-co-chlorotrifluoroethylene]-g-styrene) (P(VDF-co-CTFE)-g-SPS) was blended with polyvinylidene difluoride (PVDF), decreasing the ion exchange capacity (IEC). The blended polymers absorbed less water. However, the by AC impedance spectroscopy determined proton conductivity stayed stable or increased slightly. The effective proton mobility remained constant. Partially sulfonated poly([vinylidene difluoride-co-hexafluoropropylene]-b-styrene) (P(VDF-co-HFP)-b-SPS) with two different PS-block lengths were blended with different amounts of poly(vinylidene difluoride-co-hexafluoropropylene) (P(VDF-co-HFP)). In that case, the polymers absorbed less water and the proton conductivity decreased stepwise by adding more than 20 wt% P(VDF-co-HFP). The results indicate that a blending of P(VDF-co-CTFE)-g-SPS with PVDF inhibits swelling without having an effect on the proton conductivity, though water sorption and IEC are reduced. Brennstoffzelle Pfropfcopolymere Copolymere Diblockcopolymere Mischen Elektrolytische Leitfähigkeit Wasseraufnahme Polyelektrolyt Atom-Transfer-Polymerisation Emulsionspolymerisation Protonenmobilität PEMFC PEM Ionomer Ionenaustauschkapazität IEC PEMFC PEM Fuel Cell Proton Exchange Membrane Proton Conductivity Blending Ionomers Copolymers Proton Mobility IEC Ion Exchange Capacity Conducting Membranes Block-Copolymer Graft-Copolymer Proton-Exchange Membranes Ionomer ddc:540 Brennstoffzelle Pfropfcopolymere Copolymere Diblockcopolymere Mischen Elektrolytische Leitfähigkeit Wasseraufnahme Polyelektrolyt Atom-Transfer-Polymerisation
10	Blending of Proton Conducting Copolymers Weißbach, Thomas 08 October 2010 (has links) Highly proton conducting polymers for operation in hydrogen/oxygen proton exchange membrane fuel cells (PEMFCs) provide often a poor mechanical strength due to high water contents. To strengthen the conducting polymers, blends with different ratios of partially fluorinated sulfonic acid graft and diblock copolymers with perfluorinated polymers were prepared. To analyze the effect of the different quantities of the compounds, with regard to water sorption and proton conducting properties, membranes were prepared by dissolving the components and drop casting. Partially sulfonated poly([vinylidene difluoride-co-chlorotrifluoroethylene]-g-styrene) (P(VDF-co-CTFE)-g-SPS) was blended with polyvinylidene difluoride (PVDF), decreasing the ion exchange capacity (IEC). The blended polymers absorbed less water. However, the by AC impedance spectroscopy determined proton conductivity stayed stable or increased slightly. The effective proton mobility remained constant. Partially sulfonated poly([vinylidene difluoride-co-hexafluoropropylene]-b-styrene) (P(VDF-co-HFP)-b-SPS) with two different PS-block lengths were blended with different amounts of poly(vinylidene difluoride-co-hexafluoropropylene) (P(VDF-co-HFP)). In that case, the polymers absorbed less water and the proton conductivity decreased stepwise by adding more than 20 wt% P(VDF-co-HFP). The results indicate that a blending of P(VDF-co-CTFE)-g-SPS with PVDF inhibits swelling without having an effect on the proton conductivity, though water sorption and IEC are reduced.:1 Introduction 2 Literature Review 2.1 Fuel Cells 2.1.1 Proton Exchange Membrane Fuel Cells 2.1.2 Other Types of Fuel Cells 2.2 Proton Conductivity 2.3 Proton Conducting Polymers 2.4 Impedance Spectroscopy 2.5 Polymers 2.6 Blending 2.7 Synthesis 2.7.1 Atom Transfer Radical Polymerization 2.7.2 Emulsion Polymerization 3 Results 3.1 Synthesis 3.1.1 Polyvinylidene Diuoride (PVDF) 3.1.2 Diblock Copolymers P(VDF-co-HFP)-b-SPS and Blends 3.1.3 Graft Copolymer P(VDF-co-HFP)-b-SPS Blends 3.2 Degree of Sulfonation 3.3 Ionomer Content 3.4 Ion Exchange Capacity 3.5 Water Content and Uptake 3.6 Proton Concentration 3.7 Watermolecules per Ionic Group 3.8 Proton Conductivity 3.9 Proton Mobility 4 Discussion & Conclusion 5 Experimental Part 5.1 Synthesis 5.1.1 Synthesis of PVDF 5.1.2 Synthesis of P(VDF-co-HFP)-b-PS 5.1.3 Sulfonation of the Polystyrene Block 5.2 Polymer Characterization 5.3 Membrane Preparation 5.4 Membrane Characterization Bibliography Appendix info:eu-repo/classification/ddc/540 ddc:540

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