Poly(methyl vinyl ether-co-maleic acid)-Polyethylene Glycol Nanocomposites Cross-Linked In Situ with Cellulose Nanowhiskers

Nanocomposites were developed by cross-linking cellulose nanowhiskers with poly(methyl vinyl ether-co-maleic acid) and polyethylene glycol. Nuclear Magnetic resonance (NMR) studies showed cross-linking occurs between the matrix and cellulose nanowhiskers via an esterification reaction. Proton NMR 12 relaxation experiments provided information on the mobility of the polymer chains within the matrix, which can be related to the structure of the cross-linked nanocomposite: The nanocomposite was found to consist of mobile chitin portions between crosslinked junction points and immobilized chain segments near or at those junction points, whose relative fraction increased upon further incorporation of cellulose nanowhiskers. Atomic force microscopy images showed homogeneous dispersion of nanowhiskers in the matrix even at high nanowhisker content, which can he attributed to cross-linking of the nanowhiskers in the matrix. Relative humidity conditions were found to affect the mechanical properties of the composites negatively while the nanowhiskers content had a positive effect. It is expected that the cross-links between the matrix and the cellulose nanowhiskers trap the nanowhiskers in the cross-linked network, preventing nanowhisker aggregation subsequently producing cellulose nanocomposites with unique mechanical behaviors. The results show that in situ cross-linking of cellulose nanowhiskers with a matrix polymer is a promising route to obtain nanocomposites with well dispersed nanowhiskers, tailored nanostructure, and mechanical performance.