Degradable phosphazene-crosslinked hydrogels

Degradable hydrogels have been synthesized using a degradable crosslinker based on phosphazene derivatives. The phosphazene crosslinkers have substituted allylamine groups to provide polymerizable double bonds, and imidazole groups to control the hydrolytic stability of the crosslinker. Free radical polymerized poly(acrylic acid) gels have been formed with the phosphazene crosslinkers to demonstrate the utility of the concept. Poly(acrylic acid) gels are widely used as absorbents and there is considerable interest in finding degradable absorbent materials. Degradation of the gels occurred over a period of one to two months in aqueous media. The degradation was monitored using dynamic mechanical measurements of the modulus, static compression tests, and swelling measurements.