Preparation and characterization of nanocellulose coating modified by titanium dioxide

The hydrophilic character of cellulose nanowhiskers (CNWs) coating was changed by the use of TiO2 to modify CNWs, thus preparing TiO2/CNWs coating by a two-step method. Meanwhile, the effect of the additive amount and particle size of TiO2 on the surface structure and water contact angle (WCA) of the coatings was studied. The solid contents of the suspension were characterized by Fourier infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The TiO2/CNWs coating was characterized via scanning electron microscopy (SEM) and atomic force microscopy (AFM). Moreover, their wettability by water was revealed by the contact angle analyzer. The AFM and WCA analyses showed different additive amount and particle size of TiO2 have different effects on the surface structure and the WCA of the coatings. When the additive amount of TiO2 was 0.2 wt% and the particle size of TiO2 was 30 nm, the WCA and surface roughness (Rq) of the obtained TiO2/CNWs coating reached maximum values of 86.2° and 135nm, respectively. The TiO2 was relatively evenly distributed in the coating and the addition of TiO2 increased the crystallinity of CNWs from 79.67% to 84.89%. In addition, the FTIR and XPS analyses showed that TiO2 only physically dispersed in CNWs instead of having significant chemical reaction with CNWs.