Polymerization in the system vinylidene chloride‐potassium laurate‐potassium persulfate

The persulfate–initiated polymerization of vinylidene chloride in aqueous solutions of potassium laurate has been studied both with amounts of monomer small enough so as not to form a separate phase, and in emulsions of various compositions. In the first case, rates were determined by following the change in vapor pressure over the solution, and a method for obtaining the necessary vapor pressure‐concentration calibration curves was also developed; in the second, rates were determined by dilatometric and gravimetric methods. The rates were found to vary with the square root of the initiator concentration, and with the first power of the monomer concentration in solution, but to be independent of the amount of dispersed monomer in emulsion. They were found to increase with soap concentration, most markedly so in the region of low concentration. Approximate solubilities of monomer in polymer latices were also determined, and found to be about five times greater than solubilities in the original soap solutions; polymerization rates in emulsion and solution differed correspondingly. A high‐temperature viscometric technique has been developed for polyvinylidene chloride; intrinsic viscosity data indicate that chain transfer is appreciable in the reaction investigated.