Biopolymers gelling polymers

Formation of condensation structures is the reason for gelation of solutions of various natural and synthetic polymers. Gelation may be accompanied by conformational changes of macromolecules, which occur in the case of gelling of gelatin and other biopolymers, or in the course of chemical reactions. For instance, according to Vlodavets, partial acetalization of polyvinyl alcohol with formaldehyde in acidic medium under the conditions of supersaturation yields fibers of polyvinyl formals which further undergo coalescence and form a network with properties similar to those of leather (and artificial leather substitute). 

The formation of condensation structures is the main cause for the gelling of solutions of various natural and synthetic polymers. Gel formation may be accompanied by conformational changes of the polymer molecules, as is the case with gelatin and other biopolymers, or by various chemical interactions. Such is the acid-catalyzed synthesis of synthetic leather by the partial acetylation of polyvinyl alcohol with formaldehyde. Under supersaturation conditions, the fibers of the polyvinyl formal form in this system and develop into the network structure of synthetic leather. 

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