Anisotropic phase separation of polymer blends induced by polarization-selective photoisomerization

Abstract

SUMMARY: Anisotropic phase separation of polystyrene/poly(vinyl methyl ether) (PS/PVME) blends was induced by photoisomerization of trans-stilbene moieties labeled on the PS chains (abbreviated hereafter as PSS chains) using linearly polarized light. As temperature increases, the anisotropy becomes weaker and eventually disappears at 10 8C above the glass transition of the PSS component. It was concluded that the elastic stress associated with the spatial distribution of the reaction is responsible for this morphological anisotropy.

Phase Separation of a Polymer Mixture Driven by a Gradient of Light Intensity

“…Furthermore, phase separation in the region close to the leading edge (with the highest intensity) almost satisfies the condition of a conserved system, whereas far from this edge (in the regions with lower intensity), the kinetics is affected by the phase separating front and might become nonconserved, giving rise to the larger exponent R. Such interference processes of thermodynamic instabilities arising from spatially inhomogeneous phase separation have been observed previously in polymer blends irradiated with linearly polarized light. 13,14 From the viewpoint of practical applications, these experimental results provide not only insight into manufacturing polymeric materials with variable gradients of periodic structure but also useful information for controlling morphology of polymer blends during processing.…”