Tetragonally packed cylinder structure via hierarchical assembly of comb-coil diblock copolymer

Block copolymers constitute an important class of soft material capable of self-assembling into nanoscale microdomains with well-defined geometries. The cylindrical domains thus formed have been found to pack almost exclusively in hexagonal lattice. In this study, we disclose how the mesomorphic molecular order can mediate the packing symmetry to generate an anomalous tetragonal lattice in a diblock copolymer composing of a coil and a supramolecular comb block. This system displays a hierarchical structure in which the larger-scale cylinders formed by the coil blocks are embedded in a liquid crystalline matrix composing of a smaller-scale lamellar structure organized by the comb blocks. The cylinders are found to pack in either the typical hexagonal lattice or the tetragonal lattice governed by the orientation of the lamellae with respect to the cylinder prescribed by the overall grafting density of the comb blocks.