Directing the Interfacial Morphology of Hierarchical Structures of Dendron-Jacketed Block Copolymers via Liquid Crystalline Phases

Interfacial morphologies of hierarchically phase-separated domains in supramolecular dendron-jacketed block copolymers (DJBCP) are directed via liquid-crystalline (LC) phases of the dendronized blocks. The DJBCP is formed with a dendron 4′-(3,4,5-trioctyloxybenzoyloxy)­benzoic acid (TOB), selectively incorporated into the P4VP block of poly­(styrene)-<i>block</i>-poly­(4-vinylpyridine) (PS-<i>b</i>-P4VP). Revealed from small- and wide-angle X-ray scattering as well as transmission electron microscopy, the hexagonally packed columnar LC phase (HEX_col) of the dendronized blocks P4VP­(TOB) can substantially decrease the curvature of the intermaterial dividing surfaces (IMDS) of the DJBCP. Consequently formed are hierarchically structured DJBCP with hexagonally packed hexagon PS cylinders. As the locally two-dimensionally (2D)-ordered HEX_col phase reduces to 1D ordered smectic (Sm) phase with weakened LC packing strength, the planar IMDS of the DJBCP relaxes into curved IMDS for circular PS cylinders. IMDS flattening effect imposed by the columnar LC phase is further strengthened via a triblock DJBCP of P4VP­(TOB)_<i>x</i>-<i>b</i>-PS-<i>b</i>-P4VP­(TOB)_<i>x</i>, leading to a highly oriented honeycomb structure with an ordering length up to sub-millimeter. The LC-controlled IMDS morphology of the DJBCP might facilitate fabrication of templates toward nanoperiodic arrays with sharp channel edges for lithography applications