Synthesis of Core Cross-Linked Star Polymers Consisting of Well-Defined Aromatic Polyamide Arms

Homopolymer-arm, block-arm, and miktoarm star polymers consisting of poly(N-octyl-m-benzamide) and poly(N-H-m-benzamide) were synthesized by means of a core cross-linking method. Macromonomers (MM) with the styryl terminal moiety were synthesized by chain-growth condensation polymerization of 3-(alkylamino)benzoic acid esters 1 in the presence of phenyl 4-vinylbenzoate as an initiator, and copolymerization with N,N'-methylenebis(acrylamide) as a divinyl monomer in the presence of 2,2'-azobis(isobutyronitrile) at 60 degrees C yielded the corresponding star polymers. In the synthesis of star polymers containing poly(N-H-m-benzamide) arms, the 4-(octyloxy)benzyl group on the amide nitrogen of the obtained star polymers was removed with trifluoroacetic acid. The number of arms per molecule, determined by multiangle laser light scattering, varied in the range of 36-100 depending on the N-alkyl group of 1 and the molecular weight of MM. The H-1 NMR spectra of the star polymers in dimethyl sulfoxide revealed that the poly(N-octyl-m-benzamide) segments and arms of the block-arm and miktoarm star polymers, respectively, were compactly packed at room temperature and became extended at higher temperatures.