Applications Of Nitroxide Radical Coupling （NRC） Reaction In Synthesis Of AB₂-Shaped And Tadpole-Shaped Copolymers

For the specific structures of non-linear polymers such as star-shaped and cyclic polymers, their properties in bulk and solution are of great different with the linear ones, which shows the significant potential applications in biomedical and new materials etc. The synthesis of non-linear polymers is always an important work. Recently, the synthesis and modification of polymers are simplified tremendously because of the rapid development and applications of several living polymerization mechanisms and various coupling reactions with high efficiency. The nitroxide radical coupling (NRC) were presented and developed lately by our groups, which shows several advantages:(1) the NRC reaction shows highly efficiency;(2) the precursors can be easily prepared;(3) the NRC reactions can be carried out in wide range of temperature, which shows the potential value in designing of polymer architecture. In this thesis, new types of AB2-shaped and tadpole-shaped polymers were synthesized by NRC reaction:(1) Firstly, using DPMK as deprotonation agent, the linear poly(ethylene oxide) with a2,2,6,6-tetramethyl piperidine-1-oxyl (TEMPO) group at the middle (TEMPO-PEO2) was successfully synthesized via ring-opening polymerization (ROP) using elaborately designed initiator of4-(2,3-dihydroxypropoxy)-2,2,6,6-tetramethyl piperidine-1-oxyl (DHP-TEMPO). Then, the bromide end-functioned polystyrene (PS-Br) was synthesized via atom transfer radical polymerization (ATRP). Finally, using PMDETA/CuBr/Cu as catalyst system, the ATNRC reaction between TEMPO-PEO2and PS-Br was carried out to synthesize AB2-shaped copolymers PS-b-PEO2(2) Using TEMPO-PEO2as precursor, propargyl end-functioned TEMPO-PEO2 was obtained by modification of hydroxyl group on TEMPO-PEO2into propargyl group by reacting with propargyl bromide. Then, the macrocyclic poly(ethylene oxide) contained a TEMPO group ((c-PEO)-TEMPO) was prepared via acetylenic coupling reaction in pyridine/CuBr system. And the amphiphilic tadpole-shpaed copolymers (c-PEO)-b-(l-PS/PtBA) was synthesized by NRC reaction between (c-PEO)-TEMPO and PS-Br/PtBA-Br using PMDETA/CuBr/Cu as catalyst system.(3) The target products and intermediates were all well-defined using gel permeation chromatography (GPC), nuclear magnetic resonance (NMR) and fourier transform infrared spectroscopy (FT-IR) etc.