Janus particles with tunable shapes prepared by asymmetric bottlebrush block copolymers

Asymmetric bottlebrush block copolymers (BBCPs) containing polydimethylsiloxane and polystyrene side chains with different compositions and molecular weights (MWs) were designed and synthesized. Polymer particles were prepared by the self-organization precipitation method, in which the evaporation of the THF solvent drives the microphase separation of BBCPs. The BBCPs can self-assemble into Janus particles with different interfacial curvatures. The asymmetry and shape persistence of the macromolecular architecture of the BBCPs, resulting from the densely grafted side chains with different lengths, cause the BBCP macromolecules to pack in a different way from that of linear block copolymers (LBCPs), which ultimately affects the morphology of particles. The sizes of the particles are much larger than those of most LBCPs owing to the high MWs and the macromolecular architecture of the BBCPs. This research will significantly expand the materials library and application of Janus particles.