(Invited) Gel Behavior of Sugar-Based Polymers and Their Composites

Abstract

Cellulose is a linear sugar-based polymer and a main component of wood pulp which are a material of paper. In this decade, the cellulose nano-fibers are gathering attentions in the material science because of their mechanical properties and environmental suitability. In particular, the 2,2,6,6-tetramethyl-1-piperdinyloxy free radical (TEMPO)-oxidized cellulose nano-fiber (TOCNF) is the ultrafine fiber and have many carboxyl groups on its surface, which are suitable for the chemical modifications. From this viewpoint, we have examined the modifications of TOCNF to develop absorbers. It was demonstrated that the nanocomposites of nanoparticle/dendrimer/TOCNF allowed the diffusion of small molecules in their matrix, although the simple TOCNF formed a film with powerful gas-barrier function. Thus, the availability of these nanocomposites for absorbers were verified; however, the detailed structures of these nanocomposites were not yet confirmed. In this study, The TOCNF was hybridized with amine-polymers (poly(amido amine) dendrimer and poly(ethyleneimine) with different molecular weights). The hybrids formed transparent gels, and especially the dendrimer led to a homogeneous viscoelastic gelation in the wide range of mixing ratio. The number binding ratios of polymers per TOCNF suggested that the dendrimer partially covered the surface of TOCNF, facilitating the cross-linking, while the poly(ethyleneimine) could vary their conformations to cover the TOCNF at the different concentrations.