No abstract

We reported a new facile method to synthesize superhydrophobic nanosilica using glycidoxypropyltrimethoxysilane and dodecylamine as treatment agents. Also, we systemically investigate their performance in reinforcement of poly(dimethylsiloxane) (PDMS) rubber. Fourier transform infrared spectrum, contact angle (CA) and thermogravimetric analysis (TGA) measurements were used to characterize the modified nanosilica. Results show that the inherent hydrophilicity of parent nanosilica surface can be greatly altered through this modification method. The CA of as-prepared superhydrophobic nanosilica can reach 160.28. The properties of as-prepared modified nanosilica-filled PDMS composites were systemically investigated by dynamic rheological test, scanning electron microscopy, TGA, dynamic mechanical analysis. These as-prepared superhydrophobic nanosilica exhibit uniform dispersion in the PDMS matrix, and their composites also show good mechanical properties and distinct advantage on thermal stability compared with those of the pure silica-filled PDMS composites. Also described is the probable mechanism for the reinforcement of as-prepared superhydrophobic nanosilica-filled PDMS.

CsxWO3-ZnO-SiO2 smart coatings were proposed to achieve multiple functions, such as thermal insulation, anti-dust, anti-fogging and blocking harmful ultraviolet light, etc. The transparent hydrophobic hybrid resins were prepared from methyltriethoxysilane (MTES) and SiO2 sol, which was used as the substrate of the composite coating. The CsxWO3 is served as the near-infrared (NIR) absorber, and the ZnO is functioned as the ultraviolet (UV) blocking agent. Coatings with different ratios of CsxWO3 and ZnO were successfully prepared by co-blending with nano-SiO2 resin. The morphology, microstructure, surface composition, hydrophobicity, thermal stability, anti-dust and optical property of the composite coatings were investigated comprehensively. The transmittance of C10Z10 (CsxWO3 10%, ZnO 10%, nano-SiO2 resin 80%) coating at 370 nm is 2.3%, and the value of Solar Energy Transmittance Selectivity (SETS) is 0.665, which exhibits excellent NIR shielding ability. Compared with nano-SiO2 resin coating, the thermal insulation temperature difference can reach 7.0 °C. The C10Z10 coating showed good durability in the twenty times anti-dust repeated tests and the efficiency could maintain 70.3% after the repeating tests. The coating showed excellent sustainability after a 45-day outdoor exposure experiment and a 240 h of artificial accelerated aging experiment. Thus, the proposed CsxWO3-ZnO-SiO2 coatings are promising for outdoor smart windows.

The effects of the molar ratio of adipic acid to total diacid on the phase morphology and thermal properties of nylon copolymers containing dimer acid, adipic acid, and hexamethylenediamine were investigated. A significant structural transition from the c form to a and b mixture forms occurred with increasing molar ratio. Meanwhile, the content of the crystals increased markedly. A r-p* hyper conjugation effect was present in all of the as-prepared samples. A strong r-p* hyper conjugation effect could decrease the average distance between interchain amide groups and suppress the scission of the CAN bond through the formation of highly combining aza double-bond C¼ ¼N groups, which would, consequently, make the nylon copolymer much more stable. Differential scanning calorimetry-thermogravimetric analysis results indicate that the low thermal stability of the nylon copolymers with higher molar ratios of adipic acid to total diacid was simply due to the formation of cyclopentanone and caprolactam at 350-4208C, whereas for the nylon copolymers with lower molar ratios, the scission of the CAC bond at 430-5008C directed the pyrolysis of the main chain.

Owing to the advantages of temperature resistance, low cost, and biocompatibility, deep eutectic solvent (DES)‐based ionic conductive gels have attracted increasing research interest for flexible devices in recent years. However, current DES gels are all based on hydrophilic DES, which tend to absorb a large amount of environmental moisture, resulting in gel softening and adversely affecting the durability of the device. In this work, we highlight for the first time that N,N‐dimethylacrylamide monomer, and the obtained polymer can form hydrogen‐bonding networks with hydrophobic DES, methyl trioctyl ammonium chloride/ethyl 4‐hydroxybenzoate (1:2), thereby obtaining a hydrophobic DES‐based gel through photo‐polymerization. The resultant DES gel displays high stretchability (~900%), toughness (341.14 kJ m−3), anti‐fatigue property (recovery after 500 compression cycles), desirable conductivity (0.12 mS cm−1), adhesiveness and high transparency (>90% visible light transmittance). Notably, the hydrophobic DES‐based gel absorbs only 2 wt% water but exhibits significant water‐induced stiffening after exposing in ambient air for 1 week. These properties lead to the successful realization of the DES gels as wearable sensors to precisely monitor human motion. This work may open new avenues for the development of hydrophobic DES‐based gel ionotronics with functional performance.