Synchrotron SAXS studies on lattice structure of spherical micelles in binary mixtures of block copolymers and homopolymers

Abstract

The lattice structures of spherical micelles in binary mixtures of polybutadiene-poly(e-caprolactone) diblock copolymers and polybutadiene homopolymers were investigated using synchrotron small angle X-ray scattering technique. In the blend sample with a weight fraction of added homopolymer (Φhomo) of 40 wt%, hexagonally packed cylinders were formed, while spherical morphologies were arrayed into the Frank-Kasper a phase at Φhomo = 50 wt%. Closely packed spheres in hexagonal closely packed (HCP) and face-centered cubic (FCC) lattices were observed for the sample with Φhomo = 56 and 67 wt%, respectively. It was found that the lattices of spherical micelles assembled into the following phases with increasing Φhomo: Frank-Kasper a, HCP, and FCC phases.