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This research explores the properties of bionanocomposite films prepared by binding recombinant resilin-like protein (res) consisting of the exon 1 resilin sequence from Drosophila melanogaster engineered to include a cellulose binding domain (CBD), to cellulose nanocrystals (CNCs). The optimal binding of res-CBD to CNCs was 1:5 by mass, and the resulting res-CBD-CNCs remained colloidally stable in water. Res-CBD-CNCs were solvent cast into transparent, free-standing films, which were more hydrophobic than neat CNC films, with water contact angles of 70-80°compared to 35-40°for the latter. In contrast to the multi-domain orientation typical of chiral nematic CNC films, res-CBD-CNC and CBD-CNC films exhibited long-range, uniaxial orientation that was apparently driven by the CBD moiety. Glycerol was studied as an additive in the films to determine whether the addition of a wet component to solvate the recombinant protein improved the mechanical properties of the res-CBD-CNC films. In comparison to the other films, res-CBD-CNC films were more elastic with added glycerol, demonstrating a range of 0.5-5 wt% (i.e., the films responded more elastically to a given strain and/or were less plastically deformed by a given mechanical load), but became less elastic with added glycerol between 0.5-5 wt%. Overall, films made of res-CBD-CNCs plus 0.5 wt% glycerol displayed improved mechanical properties compared to neat CNC films, and with an increase in toughness of 150% and in elasticity of 100%.

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ZrN and Zr-SiN coatings were formed using vacuum-arc plasma fluxes deposition system at the substrate bias voltage (U B) ranged from 2 50 to 2 220 V on HS6-5-2 steel substrates. The structural, mechanical and tribological properties were characterized using x-ray diffraction, atomic force microscopy, scanning electron microscopy, optical microscopy, nanoindentation and ball-on-disk test. The surface roughness parameter Ra of ZrN coatings is lower than Zr-SiN coatings. Both roughness Ra of Zr-SiN coatings and the number of surface defects with mainly small dimensions to 1 lm decrease with increasing negative substrate bias voltage. The addition of silicon to ZrN significantly reduces the crystallite size, from about 18.3 nm for ZrN coating to 6.4 nm for Zr-SiN coating both deposited at the same U B = 2 100 V and 7.8 nm for U B = 2 150 V. The hardness of Zr-SiN coatings increases to about 30 GPa with the increase in negative substrate bias voltage (U B = 2 220 V). Adhesion of the coatings tested is high, and critical load is above 80 N and reduces with U B increase. Coefficient of friction determined using AFM shows similar trend as surface roughness in microscale.

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