Radiation‐induced polymerization and other reactions of n‐perfluoropentadiene‐1,4 at high temperature and pressure

The radiation‐induced polymerization of n‐perfluoropentadiene‐1,4 was studied at temperatures of 100–170°C. and pressures of 8,000–15,000 atm. Kinetic evidence indicates that polymerization occurs by a free radical reaction; the activation energy is between 14 and 17 kcal./mole and the activation entropy is −8 ± 5 e.u./mole. Transfer with monomer limits the number‐average degree of polymerization to values of 40 or less except in special circumstances. Dimerization and double bond migration occur to some extent; n‐perfluoropentadiene‐1,3 is formed in the latter process. It and the 1,4‐diene copolymerize; the latter undergoes cyclic addition so that the polymers are soluble and have little perfluorovinyl unsaturation. The polymers are brittle if the fraction of 1,3‐diene in the polymer is less than 0.1. They are rubbery and of considerably higher molecular weight if the fraction of 1,3‐diene is greater than 0.4. The thermal stability of the polymers decreases as the content of 1,3‐diene increases.