On the free radicals produced in γ-irradiated polyacrylamide

Abstract

Nature of free radicals produced on γ-irradiation of polyacrylamide (PAAm) have been investigated by electron spin resonance (ESR) spectroscopy. The ESR spectrum observed for irradiated PAAm at room temperature (RT) is a triplet with hyperfine (hf) splittings of 24 G and intensity distribution of 1:3:1. Superposition of component triplet, together with a singlet originating from a different radical is found to be the best fit to the experimental spectrum at RT, as has been deduced from the total curve fitting method. The ESR spectrum of irradiated PAAm at liquid nitrogen temperature (LNT) is a sharp singlet. The spectra at RT and LNT are attributed to different interconvertible forms of the free radicals of the type ∼CH₂-C(CONH₂)-CH₂-. A mechanism for radiative degradation of PAAm is proposed.

Key words:

• free radicals
• γ-irradiation
• polyacrylamide
• ESR