Phase separation in polystyrene latex interpenetrating polymer networks

Abstract

Polystyrene/polystyrene latex interpenetrating polymer networks (IPNs) were prepared by seeded emulsion polymerzation of styrene–divinylbenzene mixtures in crosslinked monodisperse polystyrene seed latexes. The resulting latexes comprised uniform nonspherical particles, which were formed by separation of the second‐stage monomer from the crosslinked seed network during swelling and polymerization. The kinetics of phase separation were investigated by examining the changes in particle morphology using optical microscopy, which revealed that the phase separation was induced by the relaxation of the polymer chains before polymerization began and was enhanced by increased conversion. The thermodynamics of phase separation were investigated by analysis of the free‐energy changes during swelling and polymerization, and the phase separation was described by a nucleation‐and‐growth mechanism. The results of this study have been applied to the design and synthesis of a series of uniform nonspherical particles of different morphology.