Interfacial properties of nano TiO₂ and cellulose paper coating

This paper examined different kinds of organic functional groups that were introduced onto the surface of nano TiO₂ by surface modification with different types of zircoaluminate coupling agents. The modified nanoTiO₂ products with different interfacial properties were obtained, and the impact of the interfacial properties of nanoTiO₂ on the rheological behavior of paper coating and the properties of coated paper was systematically investigated. The steady shear rheological results showed that the paper coatings containing nano TiO₂ exhibited a pseudoplastic fluid behavior, characterized as obvious shear thinning. Compared to the hydrophilic unmodified nano TiO₂, modified nano TiO₂ could contribute more to the viscosity of paper coatings. The study on the dynamic viscoelasticity revealed that, through the enhancing action among each component in paper coatings, the modified nano TiO₂ with quaternary amine groups or carboxyl led to a higher dynamic elastic storage modulus and viscous loss modulus of paper coatings. In addition, SEM and AFM analyses indicated that adding modified nano TiO₂ products in paper coating could improve the coating structure, thus ameliorating the optical properties and printability of coated paper. The results obtained could provide a good reference for the application of nano pigments in paper coating.