Swelling of acrylamide gels made at various onset temperatures: an optical transmission study

Abstract

AbstractOptical transmission experiments were performed using a UV–visible spectrometer during the swelling of polyacrylamide (PAAm) gels. These gels were prepared from acrylamide with N,N′‐methylenebisacrylamide at various onset temperatures (Ton) by free radical crosslinking copolymerization in water and dried before use for swelling experiments. Transmitted light intensity (Itr) from the gels increased during early stages when PAAm gels were immersed in water at room temperature and then decreased continuously as swelling time was increased. Decrease in Itr was attributed to the increase in the scattered light intensity which may originate from the contrast between ‘frozen blob clusters’ and holes in the swelling gel. Decrease in Itr was modelled using the Li–Tanaka equation from which time constants (τ1) and collective diffusion coefficients (D0) were determined for the PAAm gels prepared at different onset temperatures. τ1 and D0 were found to be dependent on Ton. The correlation between Ton and τ1 and D0 was explained in terms of the size of microgels formed during gelation.© 2003 Society of Chemical Industry