Synthesis Of UV-curable Fluorosiloxane And Research On Its Functional Coatings

Fluoropolysiloxane is a special polymer material containing the elements fluorine and silicon.The introduction of organofluorine has given organosilicone materials excellent solvent resistance and low surface energy properties,making them irreplaceable in the field of coatings.Dow corning,Shin-Etsu,and other leading companies started the research of fluoropolysiloxanes as early as the 1950s.However,our country’s fluoropolysiloxane materials still mainly rely on imports.In order to solve the problems of difficult synthesis and curing of fluoropolysiloxane,fluoropolysiloxanes with different molecular structures were designed and synthesized in this paper.Through the construction of thiol-ene light click system,efficient curing in the air atmosphere was achieved,and excellent application effects were achieved in the fields of PCB（printed circuit board）surface protection,release coating,and low surface energy functional additives.First,the synthesis of tridecafluorooctyltrimethoxysilane（FAMS-13）was studied.Through the optimization of the"three-stage"alcoholysis process,the comprehensive yield reached 84.4%.The hydrolysis law of FAMS-13 was further studied,and the multifunctional branched fluoropolysiloxanes（MA-FSR and S-FSR）containing tridecafluorohexyl groups were synthesized by the hydrolysis-condensation method.The thiol-ene photo-click system successfully overcame the problem of oxygen inhibition,and the conversion rate of double bonds reached95.37%.The research shows that the perfluoroalkyl groups will segregate to the surface,and the CF₃ group is located on the outermost surface of the coating.When the fluorine content reaches 25%,the surface energy tends to be stable,and the minimum surface energy of the coating reaches 11.5m N/m,showing excellent hydrophobicity and oil repellency.In addition,the coating also has excellent adhesion,heat resistance,and optical transparency.Compared with commercial PCB protective coatings,MA-FSR shows the advantages of rapid curing at room temperature,low surface energy,and solvent resistance.In order to further improve the dynamic liquid repellency of the coating and reduce the fluorine content,bifunctional linear fluoropolysiloxane MA-PNFMS containing nonafluorobutyl groups was designed and synthesized.Firstly,the synthesis process and polymerization rule of 1,3,5-tris（3,3,4,4,5,5,6,6,6-heptofluorohexyl）-1,3,5-trimethylcyclotrisiloxane（C4F9-D3）were studied.Based on this monomer,a hydrogen-terminated fluoropolysiloxane（PNFHMS）was synthesized by ring-opening polymerization.MA-PNFMS was prepared by selective hydrosilylation of PNFHMS with allyl methacrylate.UV curable coatings were successfully prepared with a thiol-ene photo-click system composed of S-FSR and MA-PNFMS.The research shows that the perfluoroalkyl groups will segregate to the surface,and the CF₃ group is located on the outermost surface of the coating.When the fluorine content reaches 15%,the surface energy of the coating tends to be stable,and the minimum surface energy of the coating reaches 19.0m N/m.The coating not only has excellent static liquid repellency but also has excellent dynamic liquid repellency for a series of liquids with different surface tensions.In addition,it also has excellent optical properties and aging resistance,but its mechanical properties are general.The introduction of fluorinated nano Si O₂ not only achieves the reinforcement effect but also improves the amphiphobic properties.Compared with the commercial release agent,it has the advantages of rapid curing at room temperature,solvent-free,and light release force,which provides a guarantee for the development of paperless labels.In order to meet the requirements of cost and environmental protection in the application of low surface energy coatings,a monofunctional block fluoropolysiloxane MA-FSA containing perfluoropolyether was designed and synthesized.Perfluoropolyether allyl ether（A-PFPE）was synthesized by the Williamson method.Then MA-FSA was synthesized through the hydrosilylation reaction between A-PFPE,poly（methylhydrosiloxane）,and allyl methacrylate.The organosilicon segment has better mobility,and the perfluoropolyether segment has more excellent liquid repellency.When it is added into traditional UV curing resin as a low surface energy functional additive,the surface energy can be reduced to about23 m N/m with only 1.5wt%addition,which endows the coating with excellent liquid repellency,anti-graffiti,and anti-adhesion,and the coating also has excellent adhesion and transparency.MA-FSA is applicable to different UV-curable resins.Compared with commercial products,MA-FSA has the advantages of less addition and excellent comprehensive performance.In this paper,based on the synthesis of fluorosilicone monomers,fluoropolysiloxanes with different structures were designed and synthesized,and low surface energy coatings were prepared by thiol-ene photo-click reaction.The surface chemical composition,comprehensive properties,and application effects were studied.This paper can be used for reference in the structural design,synthesis routes,and engineering applications of new fluoropolysiloxanes.