Cellulose nanofiber induced self-assembly of zinc oxide nanoparticles: Theoretical and experimental study on interfacial interaction.

In-depth understanding of interfacial behavior between biopolymer and semiconductor metal oxides is crucial to developing potential applications of their composites. A structure-ordered cellulose/zinc oxide composite was synthesized and systematically examined by a relativistic density functional theory. The prepared composite shows a hierarchical structure. ZnO nanoparticles of around 30 nm in size are found to uniformly grow along the cellulose fiber, which together construct the primary-structure unit. Associated with experimental characterizations, calculations unravel that the electrostatic attraction between cellulose and ZnO is the main driving force to form the primary structure and the subsequent electron transfer from cellulose to ZnO enhances their interfacial interaction; moreover, an exothermic process was computed. The interfacial interaction is mainly contributed by Zn-O (O denotes the cellulose oxygen atom), which is intrinsically of a dative bond; the interaction was calculated between -1.39 and -1.83 eV in strength and dominated by orbital attractions.