Preparation And Properties Of Fluorine-free And Durable Functional Superhydrophobic Materials

Superhydrophobic surface has attracted extensive attention and research in recent decades due to its special surface wetting behavior.Due to low surface energy chemistry and micro/nano structure roughness,superhydrophobic surface has excellent water repellency,which makes it important application value in anti-ice,drag reduction,self-cleaning,droplet manipulation,oil-water separation and other fields.Therefore,it is of great scientific significance and practical application value to construct different kinds of special wettable surfaces or develop new superhydrophobic surface interface functional materials for human life and production.However,the preparation of superhydrophobic materials has many problems,such as expensive equipment,harmful chemicals,time-consuming energy consumption and serious pollution.Low surface energy materials and multistage micro/nano structures on superhydrophobic surface are easily damaged by various chemical and physical conditions,leading to the failure of superhydrophobic properties.In addition,superhydrophobic materials with single function can not fully meet the needs of complex use environment,which limits their development.In the face of the above problems,this thesis mainly uses simple and environmentally friendly preparation methods,design and realize the combination of functionality and superhydrophobicity,prepare three kinds of stable and durable flexible superhydrophobic materials,and systematically study and analyze the preparation and performance of materials.The main content is summarized as the following three aspects:（1）Through 1,4-conjugate addition reaction between polyethyleneimine（PEI）and3-（trimethoxysilyl）propyl acrylate（TMSPA）,hydrolysis condensation reaction of TMSPA and dodecyltrimethoxysilane（DTMS）jointly connecting to the surface of hydrophilic silica nanoparticles,and hydrogen bond interaction of the residual amino group on the surface of PEI,the covalently crosslinked rough network structures were constructed on the fabric surfaces,and superhydrophobic cotton fabric was prepared.By adjusting the reaction time,SiO₂ concentration and TMSPA concentration,the PEI/TMSPA/SiO₂/DTMS fabric achieved the best superhydrophobicity（155.0°）.The modified fabric not only showed excellent heat resistance,excellent stability to acid,alkali,salt and organic solvents,but also had good mechanical stability to tape stripping and washing tests.The superhydrophobic,superoleophilic properties and porous structure of the modified fabric make it have excellent oil/water separation efficiency（98.49%after 18 cycles）and oil spill cleanup efficiency（95.35%after 9 cycles）.The modified fabric has the characteristics of simple preparation,environmental friendliness and easy to large-scale production,which makes it a very promising material for actual oil/water separation and oil spill cleanup.（2）A general strategy has been developed to fabricate flexible superhydrophobic PDMS/PPy-Ag/Graphene/PET coating with high conductivity and durability by means of spray,in situ redox reaction and dip coating.By adjusting AgNO₃ concentration and reaction time,the coating achieved surface resistance of 6.32Ω/□and superhydrophobicity of 154.5°.With the increase of reaction time,the micro/nano grading structure of the coating became dense and the pores decreased to disappear,leading to competition between superhydrophobicity and electrical conductivity.Superhydrophobicity and conductivity of the coating both had excellent heat resistance and UV resistance,good mechanical stability for sandpaper abrasion.The coating could still keep superhydrophobicity after immersing in acid,alkali and salt solutions of different pH.The coating showed excellent and stable electrothermal performance with fast response speed and rapid electrothermal deicing ability.At 5 V voltage,ice cube of about 0.5 cm³ completely melted and slided in 160 s.The coating also showed excellent self-cleaning,UV shielding and electromagnetic interference shielding properties.Due to its excellent superhydrophobicity and electrothermal properties,the prepared flexible multi-functional coating can be used in rapid snow melting and deicing,and has great application potential in the fields of wearable hyperthermia equipment,thermal equipment,personal thermal management and so on.（3）Durable photothermal superhydrophobic PPy/PET fabric was prepared by simple and environmentally friendly in-situ oxidative polymerization and 1,4-conjugate addition reaction.By adjusting the concentration of pyrrole monomer and octadecyl acrylate,the modified fabric showed excellent superhydrophobicity（155.8°）.The modified fabric had excellent heat resistance and UV resistance,excellent stability to acid,alkali,salt and organic solvents,and excellent mechanical stability to washing test and sandpaper abrasion.The modified fabric showed excellent and stable photothermal property,as well as excellent antifouling,self-cleaning,UV shielding performance and sun absorption ability.As an environmentally friendly and durable superhydrophobic photothermal conversion material,the modified fabric has the potential of application in the fields of photothermal deicing,seawater desalination,rapid crude oil cleanup and so on.