Development And Application Of Organic-Inorganic Hydrophilic Materials

In recent years,with the durable improvement of anti-fogging performance requirements of transparent materials have attracted many researchers studied.When the temperature is lower than the dew point of the mixture of ambient air and water vapor,the water vapor condenses and transforms into fine discrete droplets,which will cause the light transmittance of the material to decrease.So far,there are two more effective anti-fogging strategies to prevent the fog.The first strategy was to change certain environmental parameters,such as temperature,relative humidity and surrounding airflow,to avoid or eliminate water vapor condensation.The second anti-fogging strategy was to change the morphology of water droplets by adjusting the wetting characteristics of the surface,such as the(super)hydrophobicity of the surface.The agricultural greenhouse has played an active role in promoting agricultural production in China.However,the anti-fogging dripping agent added internally has a short anti-fogging flow droplet life,and it was difficult to ensure the synchronization of function and life.The gel method coated a hydrophilic polymer polyvinyl alcohol and an inorganic silica hybrid material on the surface to prepare a hydrophilic coating.The structure,morphology,wettability performance of the coating was discussed in this study.The main contents and conclusions of the study are as follows:Several different types of surfactants were added to the PVA/nano-SiO₂hydrophilic coating and coated on the surface of the polyethylene(PE)film by sol-gel dipping and pulling method.The wetting properties of the coating were tested.The surface tension of the PE film before and after corona treatment were calculated to be 33.6 and 47.2,respectively.The surface tension,wettability and coating data shows that the fluorocarbon surfactant can effectively reduce the surface tension and the sol stability.The coating also has the best anti-fogging performance.PVA/(nano-SiO₂)hybrid material was prepared by sol-gel method used nano-SiO₂ to modified PVA.The hybrid mechanism of PVA/nano-SiO₂ was analyzed.The type and content of silica sol in the hybrid material effect on hydrophilic anti-fog performance were discussed.The data showed that when the mass ratio of nano-SiO₂ to PVA was 0.8,the SiO₂ nanoparticles were uniformly dispersed in PVA to form a uniform mastoid nanostructure.The surface roughness had a magnifying effect on the hydrophilicity,which made the contact angle from 99.5°to 22.9°.The transmittance of PE film with PVA/SiO₂coating was above 90%in the best case.According to QB/T 4475-2013 standard,the anti-fogging time at 60°C was more than one month.And the hydrophilic coating has good mechanical properties can provided great practical production value.The influence of metal sodium ions on the colloidal agglomeration and stability in PVA/SiO₂ system was investigated.The Na Cl solution was added with different content in PVA/SiO₂ sol system.And the laser particle size analyzer,contact angle tester and scanning electron were used in sol system.The particle size and distribution range of the sol and the wettability and surface morphology of the coating surface were analyzed.The data showed that the surface contact angle was decreased with the addition of Na⁺.The particle size of the PVA/SiO₂ hybrid sol was increased with the addition of Na⁺.The SiO₂agglomeration occurs on the coating surface and the surface structure was destroyed.So that the anti-fogging performance of surface became poor.