Optically Active Amphiphilic Polymer Brushes Based on Helical Polyacetylenes: Preparation and Self-Assembly into Core/Shell Particles

The article reports on the first preparation and self-assembly of a unique class of amphiphilic polymer brushes, which consist of hydrophobic optically active helical polyacetylene backbones and hydrophilic thermosensitive poly(N,N-dimethylamino-2-ethyl methacrylate) (PDMAEMA) side chains. The polymer brushes were prepared by a two-step process: substituted acetylene monomers underwent catalytic copolymerizations to form optically active helical polymer backbones bearing -Br moieties in side chains, which were employed as macroinitiators for the subsequent atom transfer radical polymerization (ATRP) of a vinyl monomer DMAEMA. High specific rotations and intense circular dichroism effects demonstrated that the polymer brushes possessed optical activities, derived from the helical polyacetylene backbones. The polymer brushes could self-assemble in water/tetrahydrofuran mixture solvent to form core/shell structured nanoparticles, which showed considerable optical activity originated in the helical polyacetylene cores. The core/shell nanoparticles also exhibited thermosensitivity due to the PDMAEMA shells. This article thus provides an efficient approach for preparing novel optically active polymers and core/shell nanoparticles from helical polyacetylenes.