The mechanism of polymer chain initiation and propagation in oligo-methacryl carbonate radiation polymerizations

Abstract

ESR and diathermal calorimetric methods have been used to study the radical stage of the low temperature (77°K) radiolysis of bis-methacryloxyethylene carbonate diethylene glycol (OKM-2), also the mechanisms of polymer chain initiation and propagation during the post-polymerization. The “monomer” radicals R M forming as a results of H atom dissociation from the glycol radicals, and the H atom addition to the CC double bond of methacryl at a radiation yield of G=3±2 1/100 eV have been identified. The initiation of the polymer chain and the propagation of the macroradicals, R M+M→ R P take place at 140°K< T g=230°K. Owing to diffusive obstacles however, the polymerization is greatly inhibited and the chain growth restricted to only a few chain units. An effective post-polymerization will only take place after the thawing of the matrix and the chain propagation constant at 240-160°K will be k p ⋍0·1 exp (−22,000±2000/RT) cm 3/ sec . The radicals which were initiated by the radiolysis will entirely change into growing polymer chains (| R M| 0=| R P|) in practice and their propagation will be continuous without termination by the “live chains” mechanism; the R P radicals are stable to 350°K in a vacuum.