Polystyrene(1)/poly(butyl acrylate-methacrylic acid)(2) core-shell emulsion polymers. Part II: Thermomechanical properties of latex films

Abstract

Polystyrene(1)/poly(n-butyl acrylate-methacrylic acid)(2) structured latex particles were prepared through a two-stage emulsion polymerization procedure, using a polystyrene (PS) latex seed (118 nm), and differentn-butyl acrylate (BA)/methacrylic acid (MAA) ratios. Polymerization kinetics, particle morphology, and MAA location have already been discussed in the first part of this series. In this second part the thermomechanical behavior of films cast from these latexes was studied. Differential Thermal Analysis and Dynamic Mechanical Analysis (DMA) were employed as characterization techniques for the films. Two polymer phases corresponding to polystyrene and a poly(BA-MAA) copolymer were distinguished. Comparison was made to analogous unfunctionalized PS/PBA systems, as a result of which an effect of MAA upon the phase arrangement in the film was found. Scanning Electron Microscopy of film samples and DMA showed that the evolution of the phase arrangement as a result of annealing was strongly dependent on the type of mechanical and heat treatments being applied to functionalized systems. Finally, the thermomechanical behavior of films was related to the structural features of the corresponding latexes, and computer simulation techniques wer eemployed to establish a mechanistic support for these relationships.