Radiolysis of aqueous solutions of poly(vinyl alcohol) at 77 K

摘要

Paramagnetic products of low-temperature X-ray radiolysis of aqueous poly(vinyl alcohol) solutions (2.5 and 5% by weight) were studied by ESR spectroscopy. Experimental spectra were ascribed to a superposition of signals from hydroxyl radicals and -CH2-·C(OH)-CH2— macroradicals (C_α-macro-radicals), respectively. No ESR signals corresponding to trapped electrons were observed that was attributed to the peculiarities of microheterogenous structure of the frozen aqueous polymer solutions. Annealing at 115 K resulted in partial conversion of OH radicals to C_α-macroradicals. It was suggested that main part of hydroxyl radicals was stabilized in phase of polycrystalline ice while macroradicals were formed in "mixed" water-polymer phase. The radiation-chemical yields of paramagnetic species stabilized in the systems under study were determined.