Some peculiarities of the polymer monolayers radiolysis on the solids surfaces of different nature

Abstract

The radiolysis of some polymers monolayers at silica, aluminium oxide, soot and graphite surfaces has been studied. The obtained results indicate a considerable sensitization of radiation degradation of polymethyl methacrylate (PMMA) γ-irradiated on an aerosyl compared to in-bulk irradiation. The main reason for such sensitization is the effective transfer of the energy absorbed by aerosyl particles to their surface. The radiochemical yields of the PMMA main chain breaks ( G b) increase with decreasing of polymer molecular weights. This is caused by increasing the number of H-bonds between chain links and surface. At irradiation of polymethyl methacrylate monolayers on graphite and soot G b is 10–20 times less than on aerosyl and 2–3 times less than in-bulk. This means that graphite and soot are the protectors of the radiolysis. The obtained results are being considered on the basis of the recombination electron-hole mechanism of radiolysis. On aluminium oxide the initial PMMA G b value is close to the G b value on aerosyl, but in the field of 1–2 kGy the sharp inhibition of radiation degradation occurs: the G b value decreases 10 times. Polymethyl acrylate on the aerosyl crosslinks much more slowly than in bulk. Polystyrene on the aerosyl begin to crosslink at smaller doses than in-bulk, while the following crosslinking process on the surface proceeds less effectively than in-bulk.