Preparation of multiphase poly(styrene-co-butyl acrylate)/wax-clay nanocomposites via miniemulsion polymerization

Abstract

In the presence of different wax-clay nanocomposites concentrations, poly(styrene-co-butyl acrylate) P(S-co-BA) copolymers were prepared via free-radical random copolymerization of styrene and butyl acrylate in miniemulsion. Wax-clay nanocomposites were obtained through ultrasonic mixing at a temperature above the melting point of the wax at different clay loadings (1, 5, 7 and 10 wt%). The main objectives of this study were to obtain a good exfoliation of the clay platelets in the paraffin wax. The obtained wax-clay nanocomposites were then used as filler in the preparation of P(S-co-BA)/wax-clay nanocomposites via miniemulsion polymerization. X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicated that the clay platelets were mostly exfoliated in the paraffin wax at low concentrations, and partially exfoliated at high concentrations. The particles morphology of the P(S-co-BA)/wax-clay nanocomposite latexes was mainly determined by TEM, and the wax-clay nanocomposites were found to be encapsulated inside the P(S-co-BA) particles and that core/shell morphology was obtained. The morphology of the P(S-co-BA)/wax-clay nanocomposites (after film formation) ranged from exfoliated to intercalated structures, depending on the percentage of wax-clay nanocomposites loading. The impact of the wax-clay loading on the thermal stability and the thermo-mechanical properties of the final polymer wax-clay nanocomposites were determined.