The Morphology and Mechanical Properties of the Hybrid Films of Styrene‐Butyl Acrylate Block Copolymer/MMT From Colloid Blending

Abstract

Polystyrene/poly(butyl acrylate)/montmorillonite (PS/PBA/MMT) ternary hybrid films were fabricated by colloid blending of oligo(acrylic acid)‐functionalized core–shell particles of PS‐b‐PBA diblock copolymers and Na+‐MMT aqueous dispersions. The particles were synthesized by RAFT emulsion polymerization using oligo(acrylic acid‐block‐styrene) RAFT as a reactive surfactant. Coherent hybrid films could be formed when the particles possessed a relatively thick soft PnBA shell (core–shell ratio = 1:1 or 3:7) without adding any coalescing agent even when 15 wt% MMT was added. TEM observations revealed that around 20 nm thick clay stacks were well dispersed throughout the hybrid films. Increasing the levels of PS or MMT could much increase the modulus and tensile strength of the hybrid films. However, simply increasing PS composition would be limited by the crack formation and brittleness of the resultant films. The ternary hybrid design would allow one to gain good balance between mechanical properties and coherent film formation. The enhancing efficiency of MMT for the modulus and tensile strength was much higher when placing the clay stacks in PS domains than in PBA domains, which was particularly obvious when MMT levels were higher than 10 wt%.