Design and rheological characterization of chitin modified N-vinyl pyrollidone/Acrylamide copolymer based biphasic hydrogels

Abstract

ABSTRACT In this work, a facile synthetic procedure to develop heterogeneous biphasic hydrogel is reported using chitin/peroxide system as a precursor, with comparison with the conventional (homo-phasic) virgin hydrogels of identical formulation without any chitin in it. Structural characterization is performed using FTIR spectroscopy, and rheo-microscopy is used to investigate the stress-induced deformation of the biphasic hydrogels. This not only provides the impact of stress on the pores but also helps to investigate different phase structures present in the hydrogel systems. Rheo-microscopic study also reveals that deformation under stress is associated only with the lateral movement of the porous layers over each other. Moreover, CRYOSEM is carried out to investigate the nature of pores of the hydrogels. ~10 fold increase in storage modulus is observed for the chitin-based hydrogels as compared to conventional hydrogel. The yield stress is increased from 12 Pa to 564 Pa with the incorporation of 0.75% chitin. Chitin also induces fast swelling response to the hydrogel. The swelling time is significantly reduced from 1200 to 300 minutes due to incorporation of chitin. However, the swelling percentage at equilibrium decreases when more than 0.25% chitin is incorporated.