Crystallization of nanoscale-confined diblock copolymer chains

Crystallization of polymer chains between hard glassy walls or between amorphous domains in a nanoscale lamellar structure has been observed using simultaneous small-angle and wide-angle X-ray scattering (SAXS/WAXS). Semicrystalline symmetric diblock copolymers containing poly(ethylene) (PE) and a room-temperature glassy or amorphous component were shear oriented in the high temperature lamellar melt, then quenched below the PE melt temperature. For the glassy sample, the orientation of chain-folded PE stems was deduced from SAXS/WAXS peak positions to be parallel to the lamellar interface. Diffuse scattering bars consistent with lateral positional correlations of the PE crystallites were observed only in the SAXS patterns for the glassy sample with the X-rays incident parallel to the lamellae. In contrast, in a sample containing amorphous lamellae, PE crystallization occurred with weak crystallite orientation and no lateral positional correlations of crystallites.