Research On Preparation And Application Of Self-cleaning Coating

Due to its unique physical and chemical properties,special wettable surfaces with self-cleaning characteristics（such as superhydrophobic,superamphiphobic,etc.）have high potential value in the fields of construction,transportation and biomedical materials.The preparation of such self-cleaning surface is generally realized by constructing micro nano rough structure and adjusting the surface energy of the prepared structure.Based on this theory,from the two aspects of surface microstructure and surface energy modification,aiming at the practical problems of some self-cleaning coatings in practical application,such as aging and falling off due to poor adhesion,environmental pollution caused by the reagents used,complex process,etc.,this paper prepared a variety of practical coatings with constant temperature self-adhesive performance,anti graffiti effect and wettability regulated by charge The application value of self-cleaning coating is as follows:（1）The common industrial glue and gas phase modified silica（SiO2）were selected as raw materials,and the mixed solution was prepared by a certain proportion.The superhydrophobic self-cleaning coating with self-adhesive property was prepared by spraying process.The results show that the coating has strong adhesion to the substrate and good wear resistance.Compared with other similar studies,it solves the problem that crosslinker/modifier is easy to cause environmental pollution,and the preparation requires less raw materials and simple process*The research has been supported by the National Natural Science Foundation Project（51475353）,the open fund funded project of the State Key Laboratory for Tribology of Tsinghua University（SKLTKF14A02）,the support of the ShaanxiNatural Science Foundation Project（2016JM5004）,the scientific research project of the Key Laboratory of the Shaanxi Provincial Education Department（16JS057）,and the scientific research project of the Key Laboratory of the Shaanxi Provincial Education Department（17JS072）.flow,which is closer to practical application.（2）In this paper,polyurethane（PU）was used as the basic raw material to prepare the strength layer.PDMS,spherical SiO₂,PTFE and PFDTS were used as the raw materials to prepare the transparent anti graffiti functional layer.High strength paper with self-cleaning and anti graffiti function was obtained.The coating thickness,surface morphology and roughness were characterized by laser three-dimensional measurement microscope,SEM,EDS and AFM.The surface wettability,self-cleaning,transmittance and durability of the coating were tested.The test results show that the coating can solve the problems of existing paper easily affected by moisture,deformation,graffiti,oil pollution and tear.Moreover,the coating has good self-cleaning effect,anti graffiti ability and good resistance to oily substances.Through tensile test,the tensile strength of the paper made by this method is 6.3 times of that of ordinary paper.（3）Based on water-based paint,PFDTS,PTFE and nano-Si O₂,superamphiphobic self-cleaning coating was prepared by spraying technology.Through charge injection device,charge is injected and gathered on the coating surface,which makes the wettability of the coating surface change.By using the principle of increasing the rate of charge movement and accelerating the diffusion of charge,the wettability of the coating can be reversibly restored to superamphiphobic.SEM,EDS and Kepler microscope were used to determine the morphology and electric potential of the coating,and the fundamental cause of the change of the wettability of the coating surface was determined.This conversion process is not only different from the change of wettability through roughness and surface energy,but also overcomes the limitation of the change of wettability in traditional electric wetting phenomenon.By controlling the charge accumulation and diffusion,a high durability,convenient and reversible superamphiphobic-superamphiphilic conversion is achieved.