| Due to the advantages of abundant, renewable, biodegradable and excellent mechanical properties, nanocrystalline cellulose (NCC) has attracted considerable interesting in the field of nanotechnology. It has high Young’s modulus and strength, together with lightweight, biocompatible and self-assembly, which exhibited great promising application in nano-assembled materials and templates material preparation. In the present work, NCC suspension was prepared by hydrolysis of sulfate bleached softwood kraft pulp (BSKP) with H2SO4. Based on the self-assembly properties, NCC was used for the humidity-sensitive chiral film, mesoporous SiO2 and carbon preparation.Rod-shaped NCC was prepared from BSKP via H2SO4 hydrolysis. Effect of hydrolysis time, H2SO4 concentration and hydrolysis temperature on the morphology, potential and yield of NCC was evaluated. The results indicated that the three factors had important influence on the size and yield, while less influence on the potential. Stable NCC suspensions were obtained under certain reaction conditions (H2SO4 concentration:64 wt%, reaction temperature:45 ℃), while the size and the yield were controlled by the reaction time. NCC colloidal solution with rod-like morphology (200～400 nm in length,5～15 nm in diameter), electrical potential of -22.07 mV and high yield of 30% were obtained when the reaction time was 30 min.Humidity-sensitive chiral nematic cellulose film was prepared via evaporation-induced self-assembly method from NCC suspension. The formation of NCC liquid crystal phase, chiral nematic structure and humidity-sensitive properties of NCC film were analyzed. With the water evaporation of NCC aqueous solution, cellulose film can be formed gradually. Together with anisotropic chiral nematic liquid crystal phase can be formed spontaneously, which exhibited strong birefringence. A critical NCC concentration of 2.83 wt% was determined at which fingerprint texture of NCC film can be viewed in an optical microscope. The produced NCC film with the pitch of 1～2 μm was abundant with surface O-H functional groups, which exhibited excellent thermal stability under 200 ℃. Humidity sensitive results revealed that with the change of environmental humidity, the film exhibited different color, which indicated the great potential of this material as humidity sensor.Mesoporous silica was prepared by calcination method using NCC as template and TMOS as silica precursor respectively. Effects of template ratio on the porous structure of mesoporous silica were evaluated. The results indicated that the silica products were mesoporous materials. The pore structure and adsorption properties of the mesoporous silica were significantly influenced by the NCC/TMOS proportions. When the NCC ratio were controlled to 60 wt%, mesoporous silica with high BET surface area (628.33 m2·g-1), large pore volume (0.77 cm3·g-1) and pore size distribution among 4～10 nm were obtained, on which the highest adsorption capacity for VB12 was determined as 189.12 mg·g-1 at 25 ℃.Mesoporous carbon was prepared by carbonization-alkali etching method, using NCC as precursor and tetraethoxysilane (TEOS)/tetramethoxysilane (TMOS) as template respectively. Characterization of the products revealed that the carbon materials had excellent thermal stability, layered feature and mesoporous structure which was significantly influenced by the template ratio. When the template ratio were controlled to 50 wt%, mesoporous carbon with high BET surface area(933.90 m2-g-’), large pore volume(0.87 cm3·g-1) and pore size in range of 4-10 nm were obtained. The adsorption properties for vitamin B12 (VB12) were influenced by the pore structure and the highest adsorption capacity was determined as 336.53 mg·g-1 at 25 ℃. |
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