Branched poly(styrene-b-tert-butyl acrylate) and poly(styrene-b-acrylic acid) by ATRP from a dendritic poly(propylene imine)(NH2)(64) core

摘要

With the aim of creating highly branched amphiphilic block copolymers, the primary amine end groups of the poly(propylene imine) dendrimers DAB-dendr(NH2)(8) and DAB-dendr-(NH2)(64) were converted to 2-bromoisobutyramide groups. Poly (styrene-b-tent-butyl methacrylate) (PS-b-PtBMA) was synthesized by ATRP from the eight end group initiator, and polystyrene-b-tent-butyl acrylate) (PS-b-PtBA) was synthesized from the 64 end group initiator. The tent-butyl groups were removed to produce polystyrene-b-methacrylic acid) (PS-b-PMAA) and polystyrene-b-acrylic acid) (PS-b-PAA). Comparison of size exclusion chromatography (SEC) absolute molecular weight analyses of the polystyrenes with calculated molecular weights showed that the eight end group initiator produced a polystyrene with about eight branches, and that the 64 end group initiator produced polystyrene with many fewer than 64 branches. The PS-b-PtBA materials also have many fewer than 64 branches. The PS-b-PAA samples dissolved molecularly in DMF but formed aggregates in water even at pH 10. AFM images of the PS-b-PtBAs spin coated from THF and DMF onto mica showed aggregates. AFM images of the PS-b-PAAs spin coated from various mixtures of DMF and water at pH 10 showed flat disks and worm-like images similar to those observed with linear PS-b-PAAs. Use of a PS-b-FAA and a PS-b-PMAA as templates for emulsion polymerization of styrene produced latexes 100-200 nm in diameter. (c) 2007 Wiley Periodicals, Inc.