Browsing by Author "Schultz, Alison R."
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- Phosphonium-containing diblock copolymers from living anionic polymerization of 4-diphenylphosphino styreneSchultz, Alison R.; Fahs, Gregory B.; Jangu, Chainika; Chen, Mingtao; Moore, Robert Bowen; Long, Timothy E. (The Royal Society of Chemistry, 2015-11-20)Living anionic polymerization of 4-diphenylphosphino styrene (DPPS) achieved well-defined homopolymers, poly(DPPS-b-S) styrenic block copolymers, and poly(I-b-DPPS) diene-based diblock copolymers with predictable molecular weights and narrow polydispersities. In situ FTIR spectroscopy monitored the anionic polymerization of DPPS and tracked monomer consumption for kinetic analysis. Post-alkylation enabled controlled placement of phosphonium functionality in poly(I-b-DPPS) diblock copolymers, producing well-defined phosphonium-containing block copolymers with low degrees of compositional heterogeneity. Incorporating phosphonium charge disrupted the lamellar bulk morphology of the neutral diblock precursor and provided morphologies with interdigitated packing of alkyl chains on the phosphonium cation.
- Thermal and Living Anionic Polymerization of 4-Vinylbenzyl PiperidineSchultz, Alison R.; Jangu, Chainika; Long, Timothy E. (The Royal Society of Chemistry, 2014-07-02)Elevated temperatures that are often required for controlled radical polymerization processes lead to the thermal autopolymerization of 4-vinylbenzyl piperidine. In situ FTIR spectroscopy monitored 4-vinylbenzyl piperidine autopolymerization, and pseudo-first-order thermal polymerization kinetics provided observed rate constants (kobs). Arrhenius analysis determined the thermal activation energy (Ea) for 4-vinylbenzyl piperidine, revealing an activation energy requirement 80 kJ mol_1 less than styrene due to the presence of the piperidine ring. The similarities in chemical structure of styrene and 4-vinylbenzyl piperidine suggested a thermally initiated polymerization according to the Mayo mechanism; however, the piperidine substituent enabled a proposed cationic polymerization to enhance overall polymerization rates. In the absence of thermal polymerization, living anionic polymerization of 4-vinylbenzyl piperidine provided a viable strategy for achieving piperidine-containing polymers with predictable molecular weights and narrow polydispersities. This study also reports piperidine-containing polymeric precursors for subsequent alkylation to form novel piperidinium ionomers and polyelectrolytes.