Synthesis and self-assembly of star multiple block copolymer of poly(4-vinylpyridine)-block-polystyrene

Abstract

Star multiple block copolymer of poly (4-vinylpyridine)-block-polystyrene (s-P4VP-b-PS) is synthesized via initial synthesis of linear poly (4-vinylpyridine)-block-polystyrene (l-P4VP-b-PS) by dispersion RAFT polymerization to form l-P4VP-b-PS nano-assemblies and then cross-linking within the l-P4VP-b-PS nano-assemblies. The synthesized s-P4VP-b-PS has a high molecular weight and exists 25–47 nm nanospheres in the common solvent of N,N-dimethylformamide. The self-assembly of s-P4VP-b-PS in two block selective solvents, e.g., toluene and methanol, is investigated, and great difference from l-P4VP-b-PS is demonstrated. In methanol, s-P4VP-b-PS forms core-corona nanospheres. In toluene, s-P4VP-b-PS forms dispersed nanoparticles or nanoparticle clusters dependent on polymer concentration. In the s-P4VP-b-PS nanoparticle clusters, poly (4-vinylpyridine) forms dispersed nano-domains, the size of which is firmly dependent on the degree of polymerization of the P4VP block. It is thought that the great difference between s-P4VP-b-PS and l-P4VP-b-PS will arouse new interest on self-assembly of block copolymers.