Synthesis of Block Copoly(styrene-b-p-nitrophenyl methacrylate) and Its Derivatives by Atom Transfer Radical Polymerization

The preparation of block poly(styrene- b - p -nitrophenyl methacrylate) (PSt- b -PNPMA) and its hydrolysis and amino substitution products, poly(styrene- b -methacrylic acid) (PSt- b -PMAA) and poly(styrene-b−N-butyl methacrylamide) (PSt- b -PBMAD), were described. Polystyrene macroinitiator (PSt-Br) with narrow molecular weight distribution (MWD; M w / M n = 1.18, M n = 14 730) was prepared by ATRP using ethyl 2-bromobutyrate (EBB) as initiator and CuBr/2,2‘-bipyridine(bpy) as catalyst. Then, (PSt- b -PNPMA)s were synthesized by ATRP of NPMA using PSt-Br as initiator and CuBr/bpy as catalyst. GPC and NMR studies showed that the plot of ln([NPMA] 0 /[NPMA]) against polymerization time was linear, molecular weight ( M n ) increased linearly with conversion, and the molecular weight distributions were narrow (1.26−1.38) and became narrower as M n increased. PSt- b -PNPMA formed micelles in chloroform with PSt as shell and PNPMA as core but formed inverse micelles in dimethyl sulfoxide. PSt- b -PMAA and PSt- b -PBMAD were characterized by FTIR and NMR, but MWDs of PNPMA prepared by atom transfer radical polymerization were broad ( M w / M n = 1.57−2.45). The difference between the copolymerization and homopolymerization of NPMA was discussed.