Synthesis of an Amphiphilic Star Triblock Copolymer of Polystyrene,Poly(ethylene oxide),and Polyisoprene Using Lysine as Core Molecule

摘要

A new amphiphilic ABC star triblock copolymer,with polystyrene (PS) and polyisoprene (PI) as hydrophobic segments and poly(ethylene oxide) (PEO) as hydrophilic segment,is successfully prepared using lysine as a core molecule.The mPEO with blocked methoxyl group at one end and hydroxyl at another end,PS,and PI with hydroxyl end groups are obtained by the anionic technique.The hydroxyl groups of mPEO-OH and PS-OH are converted into succinimidyl carbonate first and then coupled with epsilon and a amino groups of lysine,respectively,to yield an intermediate mPEO-PS-Lys-COOH.The PI-OH is also converted into PI carbonate (PI-SC) and then PI-NH_2 and reacted with a carboxyl group of lysine at the junction of PS and mPEO arms of mPEO-PS-Lys-COOH in the presence of N,N'-dicyclohexylcar-bodiimide (DCC).The molecular weight distribution of the final product mPEO-PS-PI is rather narrow (<1.15).The structure of intermediates and final products was characterized by NMR,IR,UV,and SEC in detail.This method is promising for the synthesis of star copolymers with multiarms of different chain structure.