Star Block Copolymer Nanoassemblies: Block Sequence is All-Important

Zhang, Y (Zhang, Yuan)^[ 1 ] ; Guan, TY (Guan, Tianyun)^[ 1 ] ; Han, G (Han, Guang)^[ 2 ] ; Guo, TY (Guo, Tianying)^[ 1 ] ; Zhang, WQ (Zhang, Wangqing)^[ 1,3 ]

MACROMOLECULES, 2019, 52(2): 718-728

DOI: 10.1021/acs.macromol.8b02427

Abstract

Star and linear block copolymers of [poly(4-vinylpyridine)-block-polystyrene](n) [(P4VP-b-PS)(n)] and [polystyrene-block-poly(4-vinylpyridine)](n) [(PS-b-P4VP)(n)] (n = 1-4) with similar chemical composition but different block sequence were synthesized by RAFT polymerization. Star (P4VP-b-PS)(n) is composed of a jointed P4VP core and several outer PS arms, and (PS-b-P4VP)(n) has just the opposite block sequence and different conformation. The effect of block sequence on the block copolymer nanoassemblies is explored. It is discovered that star (P4VP-b-PS)(n) tends to form complicated nanoassemblies in the block selective solvent for P4VP due to the PS arms bridging, and star (PS-b-P4VP)(n) acts somewhat like linear amphiphilic block copolymers. Our study demonstrates the crucial role of block sequence in star block copolymer nanoassemblies.