On the kinetics of polymer degradation in solution: Part XI—Radiolysis of poly(olefin sulfones)

Abstract

Poly(butene-1-sulfone) (PBS) and poly(hexene-1-sulfone) (PHS) were irradiated in dilute solutions (1,4-dioxane and other solvents) with single 100 ns pulses of 16 MeV electrons from a linear accelerator. Changes of the light scattering intensity (LSI) and of the optical density (OD) after the pulse were recorded with aerated and deaerated solutions. It turned out that, with both polymers, the rate of LSI decrease (due to main-chain scission) may be correlated with the rate of fragment diffusion. Main-chain scission occurs in less than 10 μs. With poly(styrene sulfone) no change of the LSI was observed. Based on the energy absorbed by the solvent, the 100 eV yield for main-chain scissions was determined in dioxane solution with the aid of GPC as G(S) = 12 (PBS) and G(S) = 4(PHS). These results indicate that an indirect radiation effect becomes operative, mainly via energy transfer from the solvent to the polymer. OD measurements yielded evidence for the existence of a long-lived species (probably a macroradical) with a lifetime exceeding the time of fragment diffusion, which gives rise to the combination of fragments. The capability of poly(olefin sulfones) to serve as probe material for the investigation of the dynamics of macromolecules in solution is discussed.