Morphology of micron-sized polystyrene particles crosslinked with urethaneacrylate

The morphology of micron-sized polystyrene particles crosslinked with a ure thane acrylate crosslinker was studied with different concentrations of ure thane acrylate and. medium solvency by means of simple dispersion polymeriz ation. The urethane acrylate employed as a crosslinker showed an excellent effect on maintaining the monodispersity of the polystyrene particles at a moderate crosslinker concentration. (to about 5 wt%) in terms of the monome r-swellable surface of primary particles. By enhancing the medium solvency, the amount of urethane acrylate incorporated was increased, while the mono dispersity of the final particles was maintained. It was believed that the increase in solvency on adding xylene to ethanol solution helped the diffus ion of the styrene monomers into the primary particles. At high concentrati on of urethane acrylate, however, nonspherical particles, ellipsoidal or eg g-like singlets and. asymmetric doublers, were observed. The increased cros slinking density seemed to repel the styrene monomers during particle growt h.