Polymerization of miniemulsions containing predissolved polystyrene and using hexadecane as costabilizer

The effect on the polymerization kinetics of predissolving polystyrene polymers that have various molecular weights and end groups in styrene miniemulsions prepared using hexadecane as costabilizer was studied. It was noted that the rate of polymerization and number of droplets nucleated were affected by the molecular weight of the polymer that was predissolved. This dependence was attributed to a change in the number of droplets formed during homogenization as the molecular weight of the polymer was varied. However, the end group of the predissolved polymer did not have an affect on the kinetics. In all cases, predissolving polymer into a miniemulsion stabilized using hexadecane as costabilizer resulted in a much lower degree of enhancement in the kinetics compared to similar miniemulsion systems using cetyl alcohol as costabilizer. Since droplet sizes in miniemulsions containing hexadecane have been shown to be stable with time, unlike miniemulsions containing cetyl alcohol, these experiments were taken as evidence that the dominant cause for "enhanced droplet nucleation" is the preservation of droplet number prior to the addition of initiator.