Temperature-induced coordinated transformation of block copolymer micelles on fcc lattices to hcp structures

We discovered coordinated phase transformation of the strongly-segregated block copolymer micelles in aqueous solution on fcc lattices to hcp structures. The fcc structures formed by direct dissolution of poly(1,2-butadiene-b-ethylene oxide) diblock copolymer in water were gently shear-aligned and contained in sealed thin-wall capillaries. Heating the shear-aligned fcc crystallites to a higher temperature induced highly-coordinated hcp crystallites aligned in the same direction which we believe cannot happen by a nucleation and growth mechanism due to the high symmetry of fcc crystals. Careful analysis of the hcp structures suggests that the phase transformation occurred by sliding specific two-dimensional hexagonal micelle layers of the shear-aligned fcc crystallites likely with the smallest cross-section area.