LAUSR

Abstract A novel ABA-triblock bottlebrush polymer ( PS - PD - PS ), whose terminal PS block and central PD block were densely grafted with polystyrene and poly[2-(dimethylamino)ethyl methacrylate], respectively, on polynorbornene backbones was synthesized by three mutually orthogonal types of controlled polymerization. Dynamic light-scattering analysis revealed that in polar solvents such as tetrahydrofuran/water (99:1, v/v), PS - PD - PS self-assembled into oligomeric-to-polymeric aggregates through solvophobic interaction of the PS block. The size of these aggregates depended on the concentration of PS - PD - PS and on the polarity of the solvent. Atomic-force microscopy (AFM), showed that single molecules of PS - PD - PS adopted a dumbbell shape in which the three blocks in PS - PD - PS could be clearly distinguished. In AFM samples prepared under appropriate conditions, PS - PD - PS self-assembled into discrete oligomeric aggregates with well-defined structure, including linear and cyclic dimers, a tadpole-like trimer, and higher oligomers. The arrangement and junctions of the monomeric units could be clearly visualized at a single-molecular level.