The Effect of Topology on Block Copolymer Nanoparticles: Linear versus Star Block Copolymers in Toluene.

Linear and star block copolymer (BCP) nanoparticles of (polystyrene--poly(4-vinylpyridine)) (PS--P4VP) with arm numbers of 1, 2, 3, and 4 were prepared by two methods of polymerization-induced self-assembly (PISA) and general self-assembly of block copolymers in the low-polar organic solvent, toluene. The effect of the arm number on the size and/or morphology of the (PS--P4VP) nanoassemblies synthesized by the two methods in toluene and on the polymerization kinetics was investigated in detail. Our results show that in toluene, a low-polar solvent, the topology not only affected the morphology of the BCP nanoparticles prepared by PISA, but also influenced the BCP nanoparticles synthesized through general self-assembly.