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-m ethacrylic acid) (PSt-b-PMAA) and poly(styrene-b-N-butyl methacrylamide) (P St-b-PBMAD), were described. Polystyrene macroinitiator (PSt-Br) with narro w molecular weight distribution (MWD; M-w/M-n = 1.18, M-n = 14 730) was pre pared 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 stu dies showed that the plot of ln([NPMA](0)/[NPMA]) against polymerization ti me was linear, molecular weight (M-n) increased linearly with conversion, a nd the molecular weight distributions were narrow (1.26-1.38) and became na rrower 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 sulfoxi de. 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 homopolym erization of NPMA was discussed.