The hydrophilic characteristics of composite dextran gels
Polimery 1997, No 7-8, 475
Composite dextran and carboxymethyldextran gels simultaneously crosslinked covalently and coordinatively with respectively epichlorohydrin and Mg2+cations were synthesized and characterized in terms of affinity for water. In the syntheses, epichlorohydrin was used in stoichiometric proportions and in 25% and 50% molar excess over the dextran's hydroxylic groups. MgSO47H2O used as modifier was added in amounts of 0% to 40% (dextran weight basis). Swellability of the resulting materials in water was found to be related to the concentrations of the two crosslinkants (epichlorohydrin, Mg cation) and to the hydrophilicity of the polysaccharide (dextran, carboxymethyldextran). The gel synthesized with 5 wt.% MgSO47H2O was found to exhibitthe lowest swellability, 3.5 cm3/g, and the minimum water content inthe swollen state, 70.5% (Table 1, gel 6). Carboxylated dextran produced the more hydrophilic gels. The swellability data correlated well with the water contents determined in the hydrogels. The spherical shape of the particles was borne out by SEM photomicrographs (Fig. 5); the Mg2+ cation was found to affect particle surface morphology. Spatial networks are shown of a dextran composite gel (Fig. 2) and of the gels prepared with increasing magnesium contents (Fig. 8).