Synthesis And Properties Of Temperature Sensitive Biodegradable Chitosan

This dissertation used oxidant of2,2,6,6-Tetramethyl-l-piperidinyloxy(TEMPO) to oxidize free terminal hydroxyl groups of mPEG into aldehyde, when the temperature is in range of10-15℃. NaBH3CN, as the reducing agent was used in the reaction to graft mPEG onto amino of Chitosan at25℃. CS-g-mPEG is received. Using this grafting product as a crude material, the THF as the solvent, CS-g-mPEG reacted with2-Chloropionyl chloride at25℃. The result was a chitosan macroinitiator. With it as macroinitiator, PMDETA/CuCl as the catalytic system, Using atom transfer radical polymerization(ATRP) method to polymerize N-isopropylacrylamide at25℃.This dissertation applied Infrared spectroscopy(FT-IR), nuclear magnetic resonance (1H NMR) and thermo gravimetric(TG) et al to characterize the structure and properties of the products. The results shows that:The decomposition temperature of CS-g-mPEG is in166-500℃. The molar grafting degree of CS-g-mPEG is14.6%, and the molecular weight of it is242500. The solution of CS-g-mPEG is better than that of CS. The polymerization kinetics showed a good controllability. The solution of temperature sensitive biodegradable chitosan and CS-g-mPEG are similar. The LCST of temperature sensitive biodegradable chitosan was at about32℃.As the molecular weight increases, the LCST increases slightly.