The study of synthesis of poly(ethylene oxide)-b-poly(N,Ndimethylacrylamide) by atom transfer radical polymerization and self-assembly in selective solvents

Poly(ethylene oxide)-b-poly(N, N-dimethylacrylamide) (PEO-b-PDMA) was synthesized by successive atom transfer radical polymerization (ATRP) of N,N-dimethylacrylamide (DMA) monomer using PEO-Br macro initiators as initiator, CuBr and 5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazamacrocyclotetra decane (Me6[14]aneN4) as catalyst and ligand.PEO-Br macroinitiator was synthesized by esterification of PEO with 2-bromoisobutyryl bromide. GPC and 1H NMR studies show that the plot of ln([DMA]0/[DMA]) against the reaction time is linear, and the molecular weight of the resulting PDMA increased linearly with the conversion. Within 3 h, the polymerization can reach almost 60% of conversion. PEO-b-PDMA copolymer with low polydispersity index (Mw/Mn≈1.1) is obtained. Self-assembly of PEO-b-PDMA in selective solvents is also studied. It could self-assemble into micelles in methanol/acetone (1/10, v/v) solution. TEM analyses of the PEO-b- PDMA micelles with narrow size distribution revealed that their size and shape depend much on the copolymer composition.