Polymerization Behavior Of Bifunctional Diselenocabonate Mediated "Living"/Controlled Free Radical Polymerization And Its Application

Selenium-containing polymer have attracted more and more attention due to their redox sensitivity, photo sensitivity and coordinated response. These polymeric materials show potential application in optoelectronic and polymer biomaterials. Cyclic polymers also arise much of attention due to their special structure, especially no terminal groups, which showed completely different properties compared to the linear polymers. However, the synthesis of cyclic polymer was considered as a challenge work due to the difficulty in both the preparation of linear polymers with high end functionality and high efficient reactions between two ends of linear polymer. Normally, click reaction, such as Cu AAC or thiol-ene, are used for the fabrication of cyclic polymer.Our group developed new living radical polymerization system based on diselenocarbonate reagent. Polymers with high end functionality of diselenocarbonate groups were obtained under controlled manner. Similar as the polymers obtained from RAFT polymerization, these diselenocarbonate functionalized polymers could be further modified to form selenol groups, which showed much high reaction activity than thiol. At the same time, diselenide group is formed after the reaction of selenol, which showed multiresponsive behavior.Based on these considerations, the current thesis focus on the polymerization behavior of bifunctional diselenocarbonate mediated living / controlled free radical polymerization and the possible application of such polymers, the research includes the following aspects.(1) Designed and synthesized three types of bifunctional diselenocarbonates. The radical polymerization behavior of several vinyl monomers has been carried out by using these diselenocarbonates as chain transfer agents,. The polymerization showed first-order kinetic and the molecular weights of the obtained polymers increased linearly with narrow molecular weight distributions. The structure characterization through NMR and UV-vis, along with the chain extension and animolysis reaction confirmed that well-defined bifunctional diselenocabonates group as the active chain end.(2) Using the ?(11)?-difunctionalized polystyrene as the precursor, cyclic polymer with diselenide groups was synthesized through animolysis and oxidation at room temperature. By manipulating the reaction conditions and polymer concentration, several topological transformations with adjustable chain lengths were realized. The structure of obtained cyclic polymer was confirmed by the NMR, UV-vis, redox reaction and MALDI-TOF MS characterization. The diselenide-labeled cyclic polystyrene showed responsive with multi stimulus. This work provides an unprecedented and promising approach to realize the topological transformation of polymers by installing dynamic diselenide moieties into cyclic polymer, which would be useful in bio-related or physical research area.(3) Dynamic diselenide-containing polymers were synthesized by bifunctional diselenocabonate and them exchange with diselenide-containing polystyrene under visible light. The reaction was tracked by NMR and chained ratio was calculated. The Tg of the polymer was found to depending on the molar ratio. This work provides an approach that two kinds of polymer from physical blend to chemical blend.In conclusion, this thesis get well-defined bifunctional diselenocabonates group as the active chain end provides an unprecedented and promise approach to realize the topological transfor-mation of polymers by installing dynamic diselenide moieties into cyclic polymer. We also research the exchange reaction of diselenide, achieve an approach that two kinds of polymer from physical blend to chemical blend, which would be useful in bio-related or physical research area.