Nanoporous Crystalline Templates from Double-Crystalline Block Copolymers by Control of Interactive Confinement

Abstract

Single, double, and coincident crystallizations under hard or soft confinement are all carried out using a single type of syndiotactic poly­(<i>p</i>-methyl­styrene)-<i>block</i>-poly­(l-lactide) (<i>s</i>PPMS–PLLA) block copolymers. The single crystallization of <i>s</i>PPMS matrix can lead to the disordered arrangement of hexagonally packed PLLA cylinders under soft confinement. In contrast, the lamellar nanostructure remained unchanged regardless of the PLLA crystallization under hard or soft confinement. Crystallization-induced morphological transitions from the confined monosized lamella to the metastable dual-sized lamella and finally to the breakout morphology are evident by transmission electron microscopy and small-angle X-ray scattering. The dual-sized lamella is attributed to the thermodynamically and kinetically controlled nanocrystallite growth templating along the ordered microphase separation. Despite crystalline sequences, the double-crystallized morphologies are determined by the first-crystallized event even though the subsequent crystallization temperature is performed under soft confinement. By the control of interactive confinement, ordered crystalline nanosheets and cylindrical monoliths are obtained, providing a novel means for the fabrication of nanoporous crystalline templates