Synthesis and characterization of hydrogels from cellulose acetate byesterification crosslinking with EDTA dianhydride.

Abstract

Hydrogels were prepared from cellulose acetate with a degree substitution (DS) 2.5 dissolved indimethylformamide by esterification crosslinking with Ethylenediaminetetraacetic dianhydride (EDTAD)catalyzed by triethylamine. Subsequent conversion of the unreacted carboxyl groups to sodium carbox-ylates by the addition of aqueous NaHCO3was performed to enhance the water affinity of the gels. Theabsorbency of the products was strongly dependent on the amount of EDTAD that was esterified to cellu-lose acetate, and the highest absorbency was observed for the hydrogel composed of approximately 0.36molecules of EDTAD per repeat unit of cellulose acetate. The hydrogels were synthesized with differentdegrees of crosslinking and were analyzed by IR spectral (FTIR), near infrared (NIR), thermogravimetryanalysis (TG and DTG), and crosslink density evaluation by Flory-Rehner theory. The hydrogels have syn-thesized with molar ratios EDTAD/OH groups: [1/1], [1/2], and [0.1/1]. The capacity for water absorbencywas studied and compared with the water absorbency of the CA.