Radiation Induced Polymerization of β-Chloroethyl Vinylphosphonate

The gamma-ray induced bulk polymerization of β-chloroethyl vinylphosphonate was studied within the range from -78°C to 40°C The polymerization both in the liquid and the solid phases proceeded by a free radical mechanism, and the activation energy in the liquid phase was similar to that in the solid phase with the different frequency coefficients. These were 2.4 and 2.2 kcal/mol, respectively. The G-value of free radical formation was observed to be considerably large. The relationships between the rate of polymerization (Rp) or the molecular weight of the polymer (Mn) and the dose rate (I) were found to be Rp∝ I0.8 and Mn∝ I-0.22, though Mn was extremely small. These results were discussed in connection with a degradative chain transfer mechanism.