Transparent Self-Cleaning Coatings Based on Colorless Polyimide/Silica Sol Nanocomposite

We herein report transparent self-cleaning coatings based on polyimide-fluorinated silica sol (PIFSS) nanocomposite. Polyamic acid-silica sol (PASS) suspensions were synthesized by adding four different amounts of a silica sol suspension to each end-capped polyamic acid solution. The PASS suspensions were spin-coated on glass slides, thermally imidized and treated with triethoxy-1H,1H,2H,2H-perfluorodecylsilane (TEFDS) to prepare PIFSS coatings. The PIFSS coatings showed high resistance to separation from glass substrates and thermal stability. Furthermore, the PIFSS coatings on the glass substrate could be cleanly removed using polar aprotic solvents and repeated coating was possible. As the amount of silica sol particles in the PIFSS coating was increased, the hydrophobic contact angle increased. Among them, PIFSS-10 and PIFSS-15 coatings showed nearly superhydrophobic contact angles (144° and 148°, respectively) and good self-cleaning property. It was confirmed by SEM and AFM studies that their hydrophobic and self-cleaning properties are due to uniform particle distribution and relatively high surface roughness. PIFSS-10 coating showed a high transmittance value (88%) at 550 nm and good self-cleaning property, therefore suitable as a transparent self-cleaning coating. The advantages of the coating are that the fabrication process is simple, and the substrate is reusable. The PIFSS coating is expected to be applied in solar cell panels, windows, lenses and safety goggles.

Functionalizing silica sol-gel with entrapped plant virus-based immunosorbent nanoparticles

Advancements in understanding and engineering of virus-based nanomaterials (VBNs) for biomedical applications motivate a need to explore the interfaces between VBNs and other biomedically-relevant chemistries and materials. While several strategies have been used to investigate some of these interfaces with promising initial results, including VBN-containing slow-release implants and VBN-activated bioceramic bone scaffolds, there remains a need to establish VBN-immobilized three dimensional materials that exhibit improved stability and diffusion characteristics for biosensing and other analyte-capture applications. Silica sol-gel chemistries have been researched for biomedical applications over several decades and are well understood; various cellular organisms and biomolecules (e.g., bacteria, algae, enzymes) have been immobilized in silica sol-gels to improve viability, activity, and form factor (i.e., ease of use). Here we present the immobilization of an antibody-binding VBN in silica sol-gel by pore confinement. We have shown that the resulting system is sufficiently diffuse to allow antibodies to migrate in and out of the matrix. We also show that the immobilized VBN is capable of antibody binding and elution functionality under different buffer conditions for multiple use cycles. The promising results of the VBN and silica sol-gel interface indicate a general applicability for VBN-based bioseparations and biosensing applications.

Nanodiamond Batch Enriched with Boron: Properties and Prospects for Use in Agriculture

The batch of detonation nanodiamond (DB) containing impurities of B (DB-B) was obtained by explosion using TNT with hexagon (50/50). This DB-B contained 0.96 wt% of B. The obtained DB-B nanopowder's morphological features, texture, and mesostructure were investigated by SEM, SAXS, and low-temperature nitrogen adsorption. We tested both aqueous suspensions and silica sols containing 2.5 wt. % DND and 0.05-0.1 wt. % of DB-B for the pre-sowing treatment of Chinese cabbage seeds. As a result, the reliable positive effect of an aqueous suspension of DB-B (0.05-0.1 wt.%) was revealed on the following characteristics of seedlings (in relation to the control): the germination energy of Chinese cabbage seeds and germination increased by ~50-70%. Furthermore, a significant positive effect of DB-B on the morphological characteristics of Peking cabbage plants at the early stages of its development was revealed when using DB-B for pre-sowing seed treatment in combination with silica sol (an increase in the sprout length by ~ 20% and root length by ~ 50% in relation to the control) as well as the biomass of Chinese cabbage plants increased by ~ 100% (20 days after planting the treated seeds).

STUDY ON PERMEABILITY OF CUNNINGHAMIA LANCEOLATA BASED ON STEAM TREATMENT AND FREEZE TREATMENT

In order to improve the permeability of Cunninghamia lanceolata,the weight gain rate of C. lanceolatawas taken as index. The effect of time, temperature and water content on the weight gain rate of impregnated wood was analyzed by frozen and steaming treatment. By comparing the weight gain rate under different modification methods, the optimal modification process was determined.The results indicate that the optimum parameters of C. lanceolatawere saturated water content (-25°C and 8 h) at this time, the three-day gain rate of silica sol impregnated at normal temperature and pressure was 15.058%. AfterC. lanceolatais pre-treated by superheated steam, the weight gain rate of C. lanceolata, which in oven-dried specimen (120°C and 3h) contents was the highest, at this time, the three-day gain rate of silica sol impregnated at normal temperature and pressure was 15.291%.By comparing the results of pre-freezing withthe results of superheated steam treatmentof C. lanceolata,the latter will increase thepermeability of C. lanceolatabetter. Thereforesuperheated steam treatment should be chosen as an effective method for the pretreatment.

Lime compounds for restoration and decoration of building walls

Information on the effect of a polysilicate solution obtained by mixing liquid glass with a silicic acid sol on the structure formation of lime compositions is presented. It was revealed that the amount of specific heat released when lime is wetted with a polysilicate solution is greater than when lime is wetted with water. This is due to the additionally released heat due to the chemical interaction of lime with polysilicate solution. It was found that the introduction of a polysilicate solution accelerates the development of plastic strength. For comparison, we used liquid glass and a sol of silicic acid as an additive. The synergistic effect of the influence of the polysilicate solution on the structure formation of lime finishing compositions was established, which manifests itself in the acceleration of the set plastic strength in comparison with silica sol and water glass. It has been established that the introduction of a polysilicate solution into the lime mixture formulation contributes to an increase in the resistance to slipping of the finishing layer. The optimal thickness of the finishing layer was determined, which is 20 mm, at which sliding from the vertical surface is not observed.

Preparation of reduced graphene oxide and its application in chromium-free inorganic insulating coating for oriented silicon steel

In the fields of military industry, national defence and major engineering, oriented silicon steel is an indispensable material, but the chromium-containing insulating coating coated on its surface is harmful to the environment and humans. Due to poor performance, the industrialization of chromium-free inorganic coating is hindered. To improve the corrosion resistance of chromium-free inorganic insulating coating for oriented silicon steel, reduced graphene oxide (rGO) was prepared by the hydrothermal reduction method and added to the basic chromium-free inorganic insulating coating composed of small-particle silica sol, large-particle silica sol and aluminium dihydrogen phosphate to obtain rGO-containing coating. Scanning electron microscopy (SEM) and Raman spectroscopy were used to analyse the microscopic morphology and structural characteristics of rGO. Electrochemical impedance spectroscopy (EIS) and Tafel polarization curves were used to test the corrosion resistance of the coating. The results show that the prepared rGO has a multi-layer structure with a smaller size than graphene oxide (GO) and can be dispersed in water-based coatings. And rGO can reduce the corrosion current density of the coating by two orders of magnitude, and improve the corrosion resistance of the coating.