Effects of preparation approaches on optical properties of self-assembled cellulose nanopapers
As a flexible, transparent and sustainable material, cellulose nanopapers will gradually replace traditional plastic materials in “green” electronics. However, it is tedious to prepare nanopapers, and the processes have significant effects on the properties of nanopapers. Herein, after TEMPO oxidation and high pressure homogenization, cellulose nanofibrils (CNFs) were successfully produced from the softwood fibers. Then, the nanopapers were fabricated from cellulose nanofibrils using casting and vacuum filtration, and their properties, such as surface morphology, internal structure and optical properties, were examined. The nanopapers produced by casting have much smoother surfaces than those of the nanopapers prepared by filtration. As a result of the varying degrees of light scattering on the surface, nanopapers prepared by filtration present relatively high optical haze (24.2%) and good transmittance (78%) at 550 nm wavelength, whereas nanopapers produced by casting show relatively low optical haze (2.9%) and excellent transmittance (88%). Therefore, the nanopapers prepared by casting and filtration present unprecedented applications in indoor and outdoor display devices, respectively.