Photon transmission technique for monitoring swelling of acrylamide gels formed with various crosslinker contents

Abstract

Photon transmission experiments were performed using a UV–visible (UVV) spectrometer during the swelling of polyacrylamide (PAAm) gels. These gels were prepared from acrylamide (AAm) with various N, N′-methylenebisacrylamide (Bis) contents by free-radical crosslinking copolymerization (FCC) in water and dried before use for swelling experiments. Transmitted light intensity, I tr increased at very early times when PAAm gels are immersed in water, then decreased continuously as swelling time is increased. Decrease in I tr was attributed to the increase in the scattered light intensity, I sc which may originate from the contrast between ‘frozen blob clusters’ and holes in the swelling gel. Decrease in I tr was modelled using the Li–Tanaka equation from which time constants, τ 1, and collective diffusion coefficients, D o were determined for various Bis content PAAm gels. τ 1 and D o were found to be strongly correlated with the wavelength, λ, of I tr and the Bis content of the gel samples. The correlation between λ and τ 1 and D o predicts the existence of ‘frozen blob clusters’ in PAAm gels.