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Nano SiO2 is widely used in many aspects, and here are some applications of silica nanopowder in coatings.

1. Application of nano-silica SIO2 in architectural coatings
Adding nano-silica to architectural coatings can improve coating adhesion, scrub resistance, weather resistance, strength hardness, toughness, elasticity, anti-aging, anti-bacterial, anti-ultraviolet and other characteristics, significantly improve coatings’ property of self-cleaning, waterproofing, anti-seepage, anti-wear, anti-corrosion, color retention and other properties, so it has a good effect on modified exterior wall coatings.

2. Application of nano-silica in metal protective coatings
The addition of nano-SIO2 and TIO2 can increase the strength of the carbonaceous layer after the expansion of the fire retardant coating and prolong the fire resistance of the steel structure. When adding 1.5% by mass of nano-SIO2, the fire endurance of 110 min can be achieved.

3. Application of nano-silica in plastic coatings
The modified nano silica is beneficial to improve the thermal stability of the composite, delay the thermal oxidative degradation of the polyethylene, and significantly improve the flame retardant performance of the halogen-free flame retardant polyethylene. A material with better mechanical properties and flame retardancy.

4. Application of nano-silica in UV-curable coatings
Nano-silica has extremely strong UV absorption and infrared reflection properties. The spectrophotometer test shows that the absorption rate of ultraviolet light within a wavelength of 400 nm is as high as 70% or more, and the reflectance of infrared light within a wavelength of 400 nm is also more than 70%. It is added to the coating to form a shielding effect on the coating to achieve anti-UV aging and heat aging, and at the same time increase the thermal insulation of the coating.

5. Application of nano-silica in color inkjet paper coating
There are a large number of micropores and cracks on the surface of high gloss color inkjet paper. Primer can significantly improve sheet properties, and nanoscale silica provides high smoothness, absorbency, color density, and image quality.

6. Application of nano-silica in wood coatings
In the waterborne wood coating, the addition of the nano silica gel can improve the hardness of the coating film, improve the water resistance and aging resistance of the coating film, and at the same time improve the blocking resistance of the coating film. In the closed primer, the nano-silica gel has a small particle size and can be easily inserted into fine pores of wood or fiberboard. The pores are filled and sealed, and can be bonded to the substrate after drying and forming. Insoluble in water coating, which has a good sealing effect. A suitable nano-silica sol can be properly blended in the aqueous primer to accelerate the release of moisture in the primer.
It can improve the drying speed, increase the hardness of the coating film, and reduce the cost of the primer. Adding a certain nano-silica sol to the water-based topcoat has obvious improvement in water resistance, anti-blocking and hardness properties.

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Application of nano gold catalyst

There are mainly three types of nanoparticles catalysts. One is to directly use metal nanoparticles as a catalyst. This type of catalysts are mainly nano-powders of noble metals (AG, PD, PT, RH, etc.), and nano-powders of base metals such as FE, CO, and also NI have also been applied as catalyst. When some noble metal nanoparticles are used as catalysts, in addition to increasing the reaction rate, they also have good selectivity, and this selectivity is related to the particle size of the nanoparticles. The second is to load the metal nanoparticles onto the porous support as a catalyst. Commonly used carriers are porous carriers such as AL2O3, SIO2, MGO, TIO2 and activated carbon, and the supported metal nanoparticles have a particle diameter of about 1-20nm. A plurality of metal nanoparticles can be simultaneously loaded or formed into composite metal nanoparticles and loaded onto the same carrier, which can further increase the selectivity of the catalyst.

Application of nano gold catalyst
Gold has been considered as a low-activity catalytic material for a long time, but when gold is dispersed to the nano scale, it exhibits high catalytic activity. Therefore, nano gold catalysts have attracted widespread attention. Nano gold catalysts and become an important representative of nano catalysis technology. Let’s select some of the ions that have been successfully applied, which are summarized as follows:

1. Catalytic CO to CO2
The research in the past 10 years shows that when the nano Au particles are loaded onto the metal oxide by deposition or co-precipitation, the catalytic activity is very high, especially in the process of catalytic oxidation of CO to CO2 at low temperature, the catalytic ability and efficiency are better than other silicon. The metal is much higher.

2. Epoxidation of propylene
Propylene Oxide PO is an important chemical raw material used primarily in the production of polyurethane and polyol raw materials. For the gas phase in which O2 and H2 are present, the supported AU nanoparticles can catalyze the propylene to PO, and the epoxidation can be completed in one step, and no other by-products other than water.

Among the single metal oxide supports, only anatase TIO2 enables gold to selectively catalyze the oxidation of propylene to propylene oxide PO.

3. Hydrogenation of unsaturated hydrocarbons
A distinct feature of nano gold catalysts is that their partial hydrogenation is very selective: in the hydrogenation of unsaturated aldehydes, when the particle size of gold nanoparticles is greater than 2 nm, the hydrogenation selectivity ratio to C===O is C=== C is 40-50% higher. In the hydrogenation of acetylene on AU/AL2O3 and acrolein on AU/TIO2 and AU/ZRO2, the catalytic activity of the gold catalyst increases as the particle size of the AU nanoparticles decreases. This means that the metal nature of gold has an important influence on the hydrogenation of unsaturated hydrocarbons.

4. Liquid phase reaction
Ethylene glycol is oxidized to an acid in a MeOH-H2O (6:4) solvent. The gold/activated carbon catalyst is more active and selective than other precious metal catalysts and is used in the cosmetic and food industries.

5. Water-gas conversion reaction
The low temperature water-gas shift reaction has a good application prospect in polymer electrolyte fuel cells and civil electric heating systems for automobiles. A significant advantage of supported nano gold catalysts is their ability to catalyze at temperatures as low as 473K.

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Transparent flexible circuit based on silver nanowire conductive material

With the continuous development of technology, various transparent and flexible electronic devices have developed rapidly. However, compared with transparent flexible conductive materials, there are still many problems in the research of transparent flexible circuits. The research of many transparent flexible circuits only stays at the level of transparent substrate and opaque circuit. Recently, Professor Sun Jing of Dalian University has designed a transparent flexible circuit by using polydimethylsiloxane (PDMS) as a flexible substrate and silver nanowires (AgNWs) as a conductive material, which overcomes the previous transparent flexible circuit part. The drawback of transparency is the realization of a truly transparent transparent circuit. The related research work was published in Chemical Communications and was selected as the bottom article of the 5418, Volume 39, issue of 2018.

The researchers first performed experiments on PDMS, using the spin coating technique to spread the AgNWs solution evenly on the hydrophilically modified PDMS surface. The transmittance and resistance of the transparent flexible conductive material reached 90.86% and 3.22 Ω·sq-1, respectively. It is at the leading level in the field of transparent flexible conductive materials.

The research team used the mature microfluidic control technology to create holes with various complex patterns on the transparent flexible substrate PDMS surface, and the precision can reach micron level; then AgNWs are spread into these holes to make them high at the same time. Electrical conductivity. The transparent flexible circuit thus prepared has a strong wear resistance due to the protection of the channel to the AgNWs.

The transparent flexible circuit not only has good optical and electrical properties, but also has good mechanical properties. They used LEDs and ordinary dry batteries to test their electrical conductivity. The results showed that the conductivity was good. After the 180-degree inward and outward bending, 720-degree distortion and tensile test of the circuit, the brightness of the LEDs remained basically unchanged. change. The researchers further explored the application of the transparent flexible circuit, deposited Pd nanoparticles on the AgNWs of the circuit by electrodeposition, and used it to detect glucose. The results show that the sensor has high sensitivity to glucose detection.

The originality of this research is to solve two problems in the preparation of transparent flexible circuits: (1) to achieve a completely transparent flexible circuit; (2) to design circuit patterns as desired. The transparent flexible electrode prepared by the research is simple in preparation, controllable in quality and excellent in technical indicators, which can greatly promote the development of wearable electronic devices.