Synthesis and Characterization of Biodegradable Interpenetrating Polymer Networks Based on Gelatin and Divinyl Ester Synthesized from Poly(caprolactone diol)

This article describes the synthesis and characterization of interpenetrating polymer networks (TPNs) from hydrophilic and hydrophobic polymers using emulsification technique. Tween 20 (0.001 wt % of gelatin) has employed as emulsifier for the preparation of semi and full IPNs. Gelatin (G), a hydrophilic component was crosslinked by glutaraldehyde (Glu) and divinyl ester (DVE), a hydrophobic component was polymerized/crosslinked using 3 mol %, of AIBN as an initiator. Structural characterization was done using FTIR (doublet at 1620 and 1636 cm(-1)) and NMR (signals in the range of delta = 5-7 ppm), which confirmed the formation of DVE. Several samples were prepared by varying the ratio of gelatin DVE (w/w) and the Glu concentration. The swelling characteristics (as a function of varying pH maintained using buffers) and degradation behavior (in phosphate buffer saline pH 7.4) of hydrogels was studied to investigate the effect of composition and crosslinker concentration. Percent water uptake decreased from 496 to 181 at pH 7.4 and pH 6.5 in IPNs as the concentration of DVE increased from 0.3 g to 0.7 g per g of gelatin. Semi-IPNs, where DVE was not polymerized, demonstrated higher swelling at pH 7.4 in contrast to pH 6.5 irrespective of Glu concentration. Gelatin hydrogels degraded within 180 h and IPNs degraded within 290 h whereas DVE did not degrade till the study period of 20 days. The formation of IPN was confirmed by thermal characterization (DSC, TGA) and scanning electron microscopy (SEM). Observation of cross-sectional microstructure of disrupted honeycomb of Gx into closely packed fiber-like structure upon interpenetration by SEM clearly suggests the formation of IPN. (c) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 14781487,2009