Programmable Interactions of Cellulose Acetate with Octadecyltrichlorosilane-Functionalized SiO2 Nanoparticles.

It is significant to understand the interfacial interactions involved between the cellulose acetate (CA) and dispersed nanomaterials, in which the enhanced interaction improves the mechanical behavior of CA. In this work, the amendments of CA with SiO2 nanoparticles have been found to be endowed by grafting varying concentrations (0, 3, 5, and 6%) of octadecyltrichlorosilane (OTS). Aided by SiO2 colloid probe atomic force microscopy (AFM with a probe diameter of 20 µm), the adhesion force between CA and SiO2 is found to be programmable by tuning OTS concentrations functionalized onto SiO2 surfaces. The adhesion forces of 5% OTS-functionalized SiO2 with CA are the strongest, followed by the ones of 0, 3, and 6% OTS, resulting in a smoother and denser morphology on the film with 5% OTS. The AFM-measured approaching force-distance curves have been further compared to predictions by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, in which the XDLVO force is summed as the Liftshitz-van der Waals force (FLW), the electrostatic double-layer force (FEL), and the acid-base interaction force (FAB). FLW and FEL do not change significantly with OTS concentrations functionalized onto SiO2. However, FAB is sensitive to the functionalized OTS concentration onto SiO2 and significantly contributes to the interaction force of the composite films with 5% OTS, promoting the formation of a smooth and dense surface feature with a considerable mechanical performance demonstrated by load-displacement curves from a nanoindenter. This is highly encouraging and suggests that nanomaterials can be incorporated into CA to effectively improve their mechanical compatibility by programming the interaction between the CA matrix and nanomaterials.

Highly Active Hierarchical Au Nanoparticles/Cellulose@TiO2 Prepared by Surface Charge Assisted Self-Assembly.

The catalyst Au/cellulose@TiO2 with a hierarchical structure was one-pot synthesized by conventional deposition-precipitation urea method. Nanosized TiO2 particles, instead of self-agglomeration, homogeneously dispersed on the microsized microcrystalline cellulose. Simultaneously, gold particles with particle size of about 3.4 nm were mainly well-deposited on TiO2 particles. It was found that the surface charges of TiO2, cellulose and gold species played a key role in assisting in selfassembling them into the hierarchical structure. p-nitrophenol hydrogenation results displayed that the catalytic activity of Au/cellulose@TiO2 was 1.8 times and 10.9 times higher than that of Au/TiO2 and Au/cellulose, respectively. The improvement in catalytic performance of Au/cellulose@TiO2 was closely related to its hierarchical structure that influenced mass transfer of reactants and recycle of catalysts.