Reevaluation of Poly(ethylene-alt-propylene)-block-Polydimethylsiloxane Phase Behavior Uncovers Topological Close-Packing and Epitaxial Quasicrystal Growth

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Reanalysis of an uneven poly(ethylene-alt-propylene)-block-polydimethylsiloxane (PEP-PDMS) diblock copolymer first investigated in 1999 has revealed a wealthy section habits together with a dodecagonal quasicrystal (DDQC), a Frank–Kasper σ section, and a body-centered cubic (BCC) packing at excessive temperature adjoining to the disordered state. On subjecting the pattern to giant amplitude oscillatory shear properly beneath the σ-BCC order–order transition temperature (TOOT), small-angle X-ray scattering evidenced the emergence of a twinned BCC section that, on heating, underwent a section transition to an unusually anisotropic DDQC state. Surprisingly, we observe no proof of this obvious epitaxy on heating or cooling by the equilibrium σ-BCC transition. We rationalize these outcomes by way of a shear-induced order–order transition and an obvious BCC-DDQC epitaxy favored by micelle translation-mediated ordering dynamics far beneath TOOT.


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