Study On The Construction Of Special Wetted Surface Based On Anchoring Effect Of Polysilazane And The Modified Polysilazane

Special wettability surface generally refers to superhydrophobic surface with water contact angle greater than 150°and superhydrophilic surface with water contact angle less than 10°.Because of its specific hydrophobic or hydrophilic properties,it has wide application prospects in the fields of self-cleaning,anti-icing,anti-fog,fluid drag reduction,anti-biological adhesion,anti-corrosion and oil-water separation.In recent years,the surface with special wettability has become one of the important research directions in the field of surface materials.People’s research on some special wettability biomaterials in nature found that the surface chemical composition and roughness are two important factors that affect the wettability of solid surfaces.According to this theory,although the researchers have prepared artificial special wettability surface,and they have also developed some methods and techniques.However,one of the common problems is the poor stability of the prepared special wetted surface,the poor adhesion of the surface chemical structure and roughness to the substrate,which is easy to be damaged by the impact of the environment,thus losing the superhydrophilic or superhydrophobic properties.In order to solve this problem,we use organopolysiloxane（OPSZ）with excellent physical and mechanical properties and strong adhesion of multi substrate and nano particles as anchor molecules,and deposit it on the surface of the substrate together with different modified silica nano particles to build a stable superhydrophilic/superhydrophobic coating.The chemical composition,surface morphology and wettability of the special wettability coating were analyzed by modern analytical testing technology,and the anti-bacterial adhesion,self-cleaning,oil-water separation and durability of the coating were studied.In addition,the OPSZ was modified by self-made azobenzene compounds to functionalize the OPSZ to prepare a light-responsive functional coating,and to study its surface wettability and the relationship between UV/VIS light.The main contents and results of the study are as follows:（1）Preparation of V-SiO₂ with vinyl group on its surface by modifying nano-silica（SiO₂）with vinyltrichlorosilane（VTCS）.Glass was used as the substrate,and the reactive coating Glass@OPSZ@V-SiO₂ was prepared by spraying OPSZ and V-SiO₂ alternately with the surface of the substrate according to the anchoring characteristics of OPSZ.Then,the superhydrophilic coating Glass@OPSZ@V-SiO₂@DMPS was prepared by grafting the high hydrophilic zwitterionic compound（DMPS）under the UV irradiation.The results show that when the mass of VTCS accounts for 40%of the mass of SiO₂,namely 40%-V-SiO₂,the grafting amount of VTCS is the largest.When 40%-V-SiO₂ is used,the concentration of DMPS is 50 mg/m L,the prepared Glass@OPSZ@V-SiO₂@DMPS coating has the best hydrophilicity,with a water contact angle of 6.9°and an underwater oil contact angle of 142.6°,showing superhydrophilicity and high oleophobicity under water,and the adhesion to the substrate is grade 0.In addition,the prepared superhydrophilic coating Glass@OPSZ@V-SiO₂@DMPS has a significant reduction in the adhesion to S.aureus,and has a certain degree of anti-bacterial adhesion.（2）Hydrophobic N-SiO₂ nanoparticles were prepared by modifying n-dodecyl mercaptan（NDM）to V-SiO₂ via thiol-ene click reaction.Based on the anchoring characteristics of OPSZ,using a acetone dispersion of OPSZ and N-SiO₂ nanoparticles as raw materials,a series of（OPSZ/N-SiO₂）_n（n=1,2...6）coatings have been successfully constructed on glass and aluminum alloy substrates by alternately spraying layer by layer.The results show that the water contact angle of the coating surface increases with the increase of the number of double layers n.When the number of double layers n is 6,the water contact angle of Glass-（OPSZ/N-SiO₂）₆ is 160.6°,the sliding angle is 1°,the water contact angle of Al-（OPSZ/N-SiO₂）₆ is 156.7°,and the sliding angle is 2.7°,all of which show superhydrophobicity.（OPSZ/N-SiO₂）₆ coating has good durability,after 20 times of abrasive paper wear and 24 hours of immersion in strong acid and alkali,the surface water contact angle is still about 150°.In addition,CF-（OPSZ/N-SiO₂）₆ prepared with copper foam（CF）as the substrate has excellent oil-water separation performance,the separation efficiency for n-octane/water mixtures is above 95%,and for 1,2-dibromoethane/water mixtures,the separation efficiency is over 98%,and it can still maintain a high separation efficiency after repeated separation.（3）Using OPSZ as anchor molecule,the synthesis product of methylacrylic azobenzene compound MTPAP was modified on OPSZ macromolecular chain by hydrosilylation reaction to obtain the modified organicpolysiloxane OPSZ@MTPAP.Then,D-Glass-OPSZ@MTPAP coating was prepared on the surface of glass by drop casting,S-Glass-OPSZ@MTPAP coating was prepared on the surface of glass by spin coating,and CM-Ag-OPSZ@MTPAP coating was prepared on the surface of CM-Ag that copper mesh with multi-scale micro/nano composite structure by dip coating.The results show that the maximum reaction limit of OPSZ is reached when the mass ratio of OPSZ to MTPAP is 2.47:1.The prepared OPSZ@MTPAP has both the anchoring characteristics of OPSZ and the photosensitivity of MTPAP,and can produce reversible cis-trans isomerization under the irradiation of ultraviolet and visible light.After the prepared D-Glass-OPSZ@MTPA coating is exposed to ultraviolet light for 60 minutes,the water contact angle decreases from 108.1°to 98.4°,and the change value of water contact angle is 9.7°.The surface of the S-Glass-OPSZ@MTPAP surface has been exposed to ultraviolet light for 60 minutes,and its water contact angle has dropped from 106.3°to 97.7°,and the value of the water contact angle has changed to 9.6°.After 45 minutes of ultraviolet light irradiation,its water contact angle decreased from 141.2°to 123.8°,and the change value of water contact angle was 17.4°.And all have a certain cyclicity.