Influence of glass transition temperature on latex particle morphology

The effect of the combination of second stage reaction temperature and seed polymer glass transition temperature (T-g) on particle morphology was stud ied by using a polar seed polymer and a non-polar second stage polymer. Cop olymers having different ratios of MMA and MA, and thus different T-g's, we re made as seed polymers. The seed copolymers had T-g's in the 52-98 degree s C range and were used in reactions with styrene as the second stage monom er. The styrene was fed over 3.3 hours to the reactor, which was controlled at temperatures between 50 and 70 degrees C. The equilibrium morphology for these systems was inverted core-shell but it is clear from these studies that it is relatively easy to keep the non-pol ar second stage polymer from penetrating the seed particle when the reactio n temperature is less than about 15 degrees C above the seed polymer T-g fo r slow monomer feed rates. The second stage polystyrene was found to penetr ate the seed particle to different extents as the reaction temperature was increased while keeping the same radical flux to the particles.