Zwitterionic Shell-Crosslinked Micelles from Block-Comb Copolymer of PtBA-b-P(PEGMEMA-co-DMAEMA)

Through reversible addition-fragmentation chain transfer (RAFT) polymerization of t-butyl acrylate (tBA) and RAFT copolymerization of 2-dimethylaminoethyl methacrylate (DMAEMA) with poly(ethylene glycol) methyl ether methacrylate (PEGMEMA), block-comb copolymer of PtBA-b-P(PEGMEMA-co-DMAEMA) was prepared. After the self-assembly of PtBA-b-P(PEGMEMA-co-DMAEMA) into core-shell spherical micelles, P(PEGMEMA-co-DMAEMA) segments of the shell was crosslinked with 1,2-bis(2-iodoethoxy) ethane and the core of PtBA was selectively hydrolysized with trifluoroacetic acid. Thus, zwitterionic shell-crosslinked micelles with positively charged outer shell and negatively charged inner core were obtained. Dynamic light scattering, transmission electron microscope, Zeta potential measurement, and nuclear magnetic resonance were used to confirm the formation of the zwitterionic shell-crosslinked micelles. They showed the excellent resistance to the variation of pH value and possessed the positive values throughout the whole range of pH range even if the carboxylic groups of the micelles was much more than ammonium groups. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 2783-2789, 2011