Phase Behavior and Phase Diagram of Polystyrene-b-Poly(Perfluorooctylethyl Acrylates)

Abstract

Fluorocontaining polymers bearing special properties are unique and important materials in modern society. In this work, we focused on the phase behavior and phase diagram of poly(styrene-block-perfluorooctylethyl acrylate) with a volume fraction varying from 0.2 to 0.8. Small-angle X-ray scattering and transmission electron microscopy showed the phase formation in the sequence of hexagonally packed cylinders (HEX) to lamellar layers (LAM) to inverse hexagonally packed cylinders (iHEX) in this series of block polymers. Wide-angle X-ray diffraction experiments proved that the fluorodomains of the LAM phases and the matrix of iHEX phases contained layered structures formed by the crystallization of fluorosegments. During heating, the self-assembled lattice remained intact even after the melting of fluorodomain, with barely changed lattice parameters. Such hierarchical structural formation was understood by chain conformation and domain interaction, which may provide new insight into the molecular design of advanced materials.

Recent Progress in Stimuli-Induced Morphology Transformations of Block Copolymer Assemblies

“…By controlling the relative volume fraction of each block, it is possible to rationalise, and even predict in some instances, the self-assembled morphology of a given BCA at equilibrium. [7] For example, the solution conformation of a simple di-block BCA can be approximated as a cylinder or conical wedge that assembles into the morphology that achieves the most efficient packing (Figure 1). From this basic principle, it follows that a sufficient change in the relative block volume fractions of a BCA can engender a controlled transformation from one selfassembled morphology to another.…”