Hierarchical Self-Assembly in Liquid-Crystalline Block Copolymers Enabled by Chirality Transfer

Helical topological structures are often found in chiral biological systems, but seldom in synthesized polymers. Now, controllable microphase separation of amphiphilic liquid-crystalline block copolymers (LCBCs) consisting of hydrophilic poly(ethylene oxide) and hydrophobic azobenzene-containing poly(methylacrylate) is combined with chirality transfer to fabricate helical nanostructures by doping with chiral additives (enantiopure tartaric acid). Through hydrogen-bonding interactions, chirality is transferred from the dopant to the aggregation, which directs the hierarchical self-assembly in the composite system. Upon optimized annealing condition, helical structures in film are fabricated by the induced aggregation chirality. The photoresponsive azobenzene mesogens in the LCBC assist photoregulation of the self-assembled helical morphologies. This allows the construction and non-contact manipulation of complicated nanostructures.