Hydrogels based on schiff base formation between an amino-containing polyphosphazene and aldehyde functionalized-dextrans

Hydrogels generated by the interaction of two different water-soluble polymers offer access to a new group of soft materials. A prototype amino-functionalized polyphosphazene with both tyramine and ferulic acid-based side groups was coupled to aldehyde functionalized-dextrans to form hydrogels crosslinked via Schiff base chemistry. Synthesis of the polyphosphazene was accomplished by macromolecular substitution and protection-deprotection chemistry, with characterization by ¹H NMR, ³¹P NMR, solid state ¹³C NMR, and DSC techniques. Combination of the aqueous polyphosphazene and aldehyde functionalized-dextran solutions at room temperature caused gelation with different gelation times and crosslink densities dependent on the aldehyde content of the dextran. The hydrogel properties were evaluated using rheology, thermal characterization, and cryo-microscopy.