Crystallization in block copolymer melts: Small soft structures that template larger hard structures

Abstract

The crystallization of shear oriented oxyethylene/oxybutylene ͑E/B͒ diblock copolymers has been studied by simultaneous small and wide angle x-ray scattering. Crystallization of ordered melts can be accompanied by a change in length scale and retention of the melt orientation. Lamellar melts crystallize with an increase in length scale with multiply folded E blocks and the B blocks slightly stretched from their melt conformation. Crystallization from oriented gyroid melts leads to an increase in length scale with preferred melt directions being selected. The retention of layer planes on crystallization from an ordered melt is caused by the local stretching of chains and the locally one-dimensional structure, despite the relative strength of the structural process. We demonstrate that an interfacial preordering effect can cause crystallographic register to jump length scales in a soft matter system showing epitaxial crystallization.

Optical Properties of Gyroid Structured Materials: From Photonic Crystals to Metamaterials

“…The microdomains can be enlarged either by suppressing the nucleation density of the equilibrium morphology (e.g. [ 33,121,122 ] Two related and particularly promising techniques which have led to the demonstration of excellent long range order and orientational control for other block copolymer equilibrium morphologies (e.g. Their orientation might also be affected by parameters such as the commensurability between the periodicity of the equilibrium morphology and the fi lm thickness, the surface energies of the substrate-polymer and polymer-air interfaces, and the roughness of the substrate.…”

Toughening by nanostructure

“…Block copolymers have been the subject of much research over the last three decades, largely due to the interesting behaviour of amphiphilic species [25][26][27][28][29][30][31]. In these polymeric systems the blocks show differing affinity towards a potential solvent and, frequently, a tendency to avoid mixing of dissimilar blocks with one another.…”

Crystallization Kinetics

“…In the case of polyethylene, it is necessary to divide the polymer into such small volumes in order to observe something that might be homogeneous nucleation that the effect of the surfaces of the droplet might well start to play a significant role (33,34). Studies using block copolymers, although of great value, are studying nucleation in a different polymer, and the effect of connectivity to an uncrystallizable unit is complex (35).…”