Pore-Size Distributions of Cationic Polyacrylamide Hydrogels Varying in Initial Monomer Concentration and Cross-Linker/Monomer Ratio

Pore-size distributions have been measured for cationic acrylamide-based hydrogels.We use the-experimental mixed-solute-exclusion method, MSE, (introduced by Kuga) to obtain the solute-exclusion curVe representing the amount of imbibed liquid inside the gel inaccessible for a solute of radius r.We use the Brownian-motion model (developed by Cassasa) to convert the size-exclusion curve into the pore-size distribution, which gives the frequency of pore radius R as a function of R.This theoretically-based interpretation of MSEdata leads to the Fredholm integral equation that we solve numerically.'Results are reported for a series of hydro gels containing acrylamide and 3% MAPTAC; the hydrogels differed in extent of crosslinking and/or initial concentration of monomer.Pore-size distributions shift to lower pore sizes with rising initial 'monomer concentration and with rising crosslinker-to-monomer ratio.