Synthesis of ABCD 4-miktoarm star-shaped quarterpolymers by combination of the "Click" chemistry with multiple polymerization mechanism

Well-defined ABCD 4-Miktoarm star-shaped quarterpolymers of [poly(styrene)-poly(tert-butyl acryl ate)- poly(ethylen e oxide)-poly(isoprene)] [star(PS-PtBA-PEO-PI)] were successfully synthesized by the combination of the "click" chemistry and multiple polymerization mechanism. First, the poly(styryl)lithiurn (PS-Li+) and the poly(isoprene)lithium (PI-Li+) were capped by ethoxyethyl glycidyl ether (EEGE) to form the PS and PI with both an active omega-hydroxyl group and an omega'-ethoxyethyl-protected hydroxyl group, respectively. After these two hydroxyl groups were selectively modified to propargyl and 2-bromoisobutyryl group for PS, the resulted PS was used as macroinitiator for ATRP of tBA monomer and the diblock copolymer PS-b-PtBA with a propargyl group at the junction point was achieved. Then, using the functionalized PI as macroinitiator for ROP of EO monomer and bromoethane as blocking agent, the diblock copolymer PI-b-PEO with a protected hydroxyl group at the conjunction point was synthesized. After the hydrolysis, the recovered hydroxyl group of PI-b-PEO was modified to bromoacetyl and then azide group successively. Finally, the "click" chemistry between them was proceeded smoothly. The obtained star-shaped quarterpolymers and intermediates were characterized by H-1 NMR, FT-IR, and SEC in detail. (C) 2008 Wiley Periodicals, Inc.