Interconnected microdomain structure of crosslinked cellulose nanocomposite revealed by micro-Raman imaging and its influence on water permeability of film.

Abstract

The substantial adsorption of water-vapor triggered by hydrogen-bonding interactions between water molecules and cellulose chains (or nanoplates) is hard to be avoided in nanocomposite films, although the addition of nanoplates can improve the oxygen (or carbon dioxide) barrier properties. In present work, an effective strategy is raised to decline adsorption by weakening hydrogen-bonding interactions via chemical crosslinking by epichlorohydrin (ECH) without the sacrifice of homogeneous dispersion of nanoplates. The generated microdomain structure of chemical crosslinking reaction via ECH is explicitly revealed by micro-Raman imaging. Unambiguously, Raman maps of scanning elucidate the distribution and morphology of physical and chemical crosslinking domains quantitatively. The chemical crosslinking domains nearly uniformly locate in the matrix at a low degree of crosslinking, while the interconnected and assembled networks are formed at a high crosslinking degree. ECH boosts the formation of chemical crosslinking microdomains, bringing out the terrific water-vapor-barrier property and alleviating the interfacial interactions in penetration, consequently magnifying the water contact angle as well as holding back the water-vapor permeability. Our methodology confers an effective and convenient strategy to obtain remarkable water-vapor resistant cellulose-based films meeting the practical application in the packaging fields.