Synthesis Of Heteroarm Star-Shaped (Polystyrene)_n-[Poly(Ethyl Acrylate)]_m Via Atom Transfer Radical Polymerization

Heteroarm star-shaped polymer, (polystyrene)_n-[poly(ethyl acrylate)]_m [(PS)_n-(PEA)_m], where the arm number of PEA was greater than that of PS, was synthesized via atom transfer radical polymerization (ATRP). In contrast, heteroarm star-shaped polymers were usually A_nB_n which arm number of A and B were same.(PS)_n-(PEA)_m was synthesized in three steps. In the first step, star-shaped polystyrene, (PS)_n, was synthesized by the arm-first method via ATRP using a preformed PS macroinitiator obtained by ATRP of styrene, in the presence of divinyl benzene (DVB). In the microgel core of (PS)_n, there were a number of active initiating sites for ATRP, 1-bromoethylbenzene groups, which were from the addition of linear PS macrointiators to vinyl groups of DVB. Their number was theoretically equal to that of PS arm. In addition, some unreacted vinyl groups would...