Spherical Gels of Polyacrylamide Imidized by Heat-treatment

Abstract

Aqueous solutions of acrylamide and N, N'-methylenediacrylamide were suspended in a toluene-chlorobenzene mixture and spherical porous gels were obtained. By subsequent heattreatment of the gels, porous hydrophilic gels of various degree of imidization were produced. By eluting water soluble materials, such as acetone, ethylene glycol oligomers of various molecular weights and Blue Dextran, through columns packed with gels, the calibration curves were constructed. The increase of degree of imidization of gels shifted the calibration curves to the range of lower molecular weight without causing any variation in slope, and decreased log M_11m to a significant extent.
For the gel of 4.87 mol% crosslinking agent in total monomer, its excluded molecular weight, degree of swelling wet-mi/dry-m0 and amount of water regain (g/dry-g) were 14000, 4.81 and 4.67, respectively. When imidized at the heat-treatment temperature of 245° C for 2 hr, the degree of imidzation reached 63.0 mol%. Its excluded molecular weight, degree of swelling and amount of water regain were 150, 1.33 and 1.41, respectively. Among the gels of 4.87, 9.29 and 13.29 mol% crosslinking agent in total monomer, the 4.87 mol% gel turned out to be imidized most effectively.