Reduced graphene oxide (RGO) sheets were covalently assembled onto silicon wafers via a multistep route based on the chemical adsorption and thermal reduction of graphene oxide (GO). The formation and microstructure of RGO were analyzed by X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, Raman spectroscopy, and water contact angle (WCA) measurements. Characterization by atomic force microscopy (AFM) was performed to evaluate the morphology and microtribological behaviors of the samples. Macrotribological performance was tested on a ball-on-plate tribometer. Results show that the assembled RGO possesses good friction reduction and antiwear ability, properties ascribed to its intrinsic structure, that is, the covalent bonding to the substrate and self-lubricating property of RGO.

Polymer nanocomposite microspheres (PNCMs) as solid supports can improve the efficiency of immobilized enzymes by reducing diffusional limitation as well as by increasing the surface area per mass unit. In this work, pectinase was immobilized on Fe(3)O(4)/SiO2-g-poly(PSStNa) nanocomposite microspheres by covalent attachment. Biochemical studies showed an improved storage stability of the immobilized pectinase as well as enhanced performance at higher temperatures and over a wider pH range. The immobilized enzyme retained >50% of its initial activity over 30 days, and the optimum temperature and pH also increased to the ranges of 50-60 degrees C and 3.0-4.7, respectively. The kinetics of a model reaction catalyzed by the immobilized pectinase was finally investigated by the Michaelis-Menten equation. The PSStNa support presents a very simple, mild, and time-saving process for enzyme immobilization, and this strategy of immobilizing pectinase also makes use of expensive enzymes economically viable, strengthening repeated use of them as catalysts following their rapid and easy separation with a magnet.

The mechanical and tribological performance of the PA66/PVDF blends filled with various amount of calcium sulphate whiskers (CSW) was investigated. The whiskers improve the tensile and flexural performance of the PA66/PVDF blends. Meanwhile, the addition of CSW obviously decreases friction coefficient and improves the wear resistance of the blends. With the further increase of CSW, friction coefficient of the blends relatively keeps stable and the wear resistance of the blends slightly decreases. The PA66/PVDF blends filled with 5 wt% CSW exhibited the best anti‐wear ability. FTIR analysis shows that the chemical change has not occurred in the debris. XPS analysis shows that some tribo‐chemical reactions have occurred during friction process and produces some compounds such as FeF2, Fe2O3 on the transfer film surfaces. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers