Abstract
| - Semi-interpenetrating networks (SIPNs) of poly(N,N-dimethylacrylamide) (DMAm) containing cellulose or chitin were prepared in 9%LiCl/N,N-dimethylacetamide (DMAc) as the homogeneousreaction medium. N,N-Methylenebisacrylamide (MBAm) was utilized as the cross-linking agent with2,2‘-azobisisobutyronitrile (AIBN) as the initiator. The respective SIPNs contained 25, 12, and 6 wt %cellulose or 6 wt % chitin. A control DMAm hydrogel (without polysaccharide) was also synthesized in9%LiCl/DMAc. The 25 wt % cellulose DMAm SIPN was found to be unique, differing from the othercompositions prepared, possessing a 6-fold higher modulus than the DMAm control. The enhancementin mechanical stiffness was attributed to intimate molecular interactions and complexation betweencellulose and DMAm. The presence of the extended cellulose chains within the DMAm matrix creates amore open network in the nonsolvated state as reflected in DSC and fluorescence experiments. It is thismolecular level interaction of cellulose with DMAm that enhances the physical properties in the firstSIPN composite to utilize unmodified cellulose and chitin. In the solvated state, the microdispersedpolysaccharide hydrogen bonds with the DMAm matrix increases the rigidity of the network yet allowsreversible hydration as reflected in rheology, equilibrium swelling, and fluorescence experiments.
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