The Synthesis And Modification Of Polymers End-capped By Diselenocabonate Moieties

Recently, many researchers have an increasing interest in selenium-containing polymers. In organic optoelectronic devices, selenophene polymers have a great development by only few years. Selenophene polymers have got similar, even better effect than thiophene polymers based organic optoelectronic devices, they have potential broad application in photoelectric materials. In biomaterials, selenium-containing polymers are low mammalian toxicity, because selenium is an essential microelement for mammalian being. And due to selenium’s electronegativity and atomic radius, selenium-containing polymers has become special polymers with unique and mild stimuli-responsive like dual redox responsive, red light responsive, coordination responsive and so on. Those show their potential application as mild – responsive drug delivery vehides.The synthetic routes towards selenium-containing polymers have been developed since many years ago. So far, the synthetic routes included: polymerization of selenium-containing monomers which is the most popular mothed in application; Iniferterpolymerization by using organic selenium compounds; organoselenium-mediated CRP reported by our group; modification of polymer by ATRP and so on. In those,the mothed, organoselenium-mediated CRP which can be used in polymerization of typical vinyl monomers, get polymers end-capped by diselenocabonate moieties.This thesis continue to focus on the research of polymerization using organoselenium compounds. And this thesis began to focus on modification of polymers end-capped by diselenocabonate moieties. The research include the fllowing aspects.(1) The atom transfer radical polymerizations(ATRPs) of styrene(St) initiated by diselenocarbamates were carried out for the first time. The polymerization showed first-order kinetic with respect to the monomer concentration, and the molecular weights of the obtained polymers increased linearly with the monomer conversions with narrow molecular weight distributions. The results of chain extension, 1H NMR and UV-vis spectra confirmed that well-defined polystyrene bearing a N, N-(diethylamino) diselenocarbamoyl group as the active chain end was obtained via ATRP of St with diselenocarbamate as an initiator.(2) In this work, the synthesis of diselenide(Se-Se)-labeled polymers based on diselenocabonate-mediated controlled radical polymerization(CRP) was investigated. Diselenocabonate-end capped polymers from diselenocabonate-mediated CRP were transformed to diselenide-centered polymers through high-efficiency aminolysis and spontaneous oxidation coupling reaction in an open system. The process of aminolysis and spontaneous oxidation of the polymer chain ends was monitored by UV-Vis, GPC and NMR characterizations. The obtained diselenide-centered polymers showed reversible redox-responsive behavior. This work provides a protocol of introducing redox responsive Se-Se bond into the polymer backbones. Importantly, the molecular weight and architectures of the diselenide-containing polymer can be well defined.(3) Diselenocabonate-end capped polymers were transformed to diselenide-centered polymers through high-efficiency aminolysis and spontaneous oxidation coupling reaction in an open system. Diselenocabonate-end capped polymers were transformed to seleno-end capped polymers through aminolysis, in nitrogen and reductive atmosphere. Then halohydrocarban or MMA, nuclear receptor, was added for modification of polymers. The polymer chain ends was monitored by UV-Vis, GPC, NMR and MALDI-TOF characterizations.