INTERFACIAL ASPECTS OF LATEX IPNS FOR TOUGHENING POLYCARBONATE .1. SYNTHESIS AND CHARACTERIZATION

Core/shell structured latex particles with an interpenetrating polymer network (IPN) core (polymer A and polymer B) and glassy shell (polyme r C) were synthesized by emulsion polymerization techniques. Polymer A was poly(butadiene-stat-styrene) (90/10) (P(Bd/S)). Polymer B was eit her poly(butyl acrylate-stat-methyl methacrylate) (60/40) or poly(buty l acrylate-stat-styrene) (60/40) prepared by a sequential IPN techniqu e to form the cores. The glass transition temperatures, T-g, of polyme r A and polymer B were around -70 and 10 degrees C, respectively. The shell, polymer C, poly(styrene-stat-acrylonitrile) (72/28), was polyme rized with grafting onto the IPN core by a semicontinuous process. The particle size and particle size distribution were measured by light-s cattering, capillary hydrodynamic fractionation, and transmission elec tron microscopy. The glass transition temperatures were determined by differential scanning calorimetry. The polymer A (particle sizes betwe en 200-270 nm) with different gel fractions was used to characterize t he effect of gel fraction on IPN morphology. A core/shell type phase s eparation was observed for IPN particles when using a polymer A with > 90% gel fraction. A distribution of polymer B domains in polymer A wa s obtained when using polymer A with a 40% gel fraction. A good covera ge of polymer C on the IPN core particles was obtained at a core/shell ratio of one to one. A broad glass transition range for the core/shel l structured latex particles was observed. In article II of this serie s, these latex particles will be used to toughen such engineering ther moplastics as polycarbonates to understand the particular toughening t heories of these polymers. (C) 1995 John Wiley & Sons, Inc.