Heterogeneity of the Pores of Polysaccharide Gels: Dependence on the Molecular Weight and Derivatization of the Polysaccharide

By digital image analysis of thin sections observed by electron microscopy, the finding is made here that reducing the molecular weight of derivatized agarose causes an increase in the heterogeneity of the size of pores in gels formed by the derivatized agarose. A similar effect is found for gels formed by underivatized curdlan. The structure of underivatized agarose gels is less sensitive than the structure of derivatized agarose gels to lowering the molecular weight of the agarose. Heterogeneity is promoted by raising the temperature of gelation. Spontaneous nucleation, not a previously demonstrated pregelation phase separation, is a mechanism that explains the dependence of heterogeneity on both temperature and agarose molecular weight.