Phase separation in a mixture of poly(ether sulphone) and poly(ethyl oxazoline): observation in real and reciprocal spaces

Abstract

A mixture of poly(ether sulphone) and poly(ethyl oxazoline) was found to exhibit the lower critical solution temperature ( LCST) type phase behaviour. The kinetics of phase separation after the temperature jump from the single-phase region to the two-phase region above the LCST was investigated in both real and reciprocal spaces, i.e. by light scattering, scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM) and optical microscopy. The four different observations yielded an identical time variation of the periodic distance in the phase-separated structure. The early stage was well described within the framework of Cahn's linearized theory. In the late stage, the self-similarity in the structure was maintained throughout the coarsening process and the kinetics was described by the cluster dynamics by Binder and Stauffer. Unfortunately, direct observation of the concentration profile by elemental analysis by STEM was impossible.