Cross-linking xanthan and other compounds with glycerol

Abstract

In a waterless or near-waterless environment glycerol's hydroxyl groups react with xanthan's functional groups to make glycerol cross-linked xanthan (GCX) since not enough water is present to inhibit glycerol-xanthan reactions. The water, formed during cross-linking, in fact catalyzes the unwinding of xanthan's double-helix thus making functional groups of its side chains and of its backbone more accessible for cross-linking. Functional groups of xanthan's side chains and those in its backbone are cross-linked with glycerol monomers and oligomers. Glycerol monomers and its oligomers cross-link xanthan when glycerol to xanthan weight ratio is smaller than 27.6. Hardness increases with an increase of xanthan to glycerol ratio; GCX made with 50% wt xanthan is a hard solid material almost 40 times harder than GCX gel made with 5% wt xanthan. A gram of GCX absorbs more than 39 g of water. In a waterless or near-waterless environment glycerol cross-links xanthan and other bio-polymers. Materials made by glycerol cross-linking of bio-polymers can be used as hydrogels, absorbents, coatings, carriers in controlled delivery of chemicals, films, membranes and are of interest for those and other applications in agriculture, food, pharmaceutical and other industries. Using glycerol to cross-link bio-polymers and other compounds will also help decrease the pressure on the water resources and minimize pollution of the environment.