The Research About Preparation And Application Of Two Functionalized Materials With Special Wettability

Inspired by delicate microstructure and special wettability in nature,researchers have prepared a series of special wetting materials by imitating nature,which were widely used in the fields of waterproof,anti-icing,anti-pollution,anti-corrosion,oilwater separation,self-cleaning,directional micro-flow transportation,etc.In recent years,the preparation of special wettable surface has been continuously optimized from the simplest natural template method to the direction of precise design and special function with the development of surface science and technology.However,the largescale industrial production of special wetting materials is still limited by many factors.The oily contaminated liquids with a low surface tension coefficient cannot be repeled by the highly hydrophobic surface.Although the superoleophobic materials can resist invasion of liquid with low surface tension coefficient,the microscopic design of the materials is very complicated,and the mechanical stability is difficult to guarantee the practical long-term performance.The lubricant will be lost when the oil-infused antifouling material is subjected to high temperature and long-term wear.Besides,the compatibility of base material with lubricant and the preferential wetting between probe liquids and substrate material should be considered.Flexible polymer chain with low surface energy is used to grafted on slippery surface to repel liquids with low surface tension.However,many grafting processes need complex chemical reaction,special temperature and atmosphere,and the prepared slippery surface cannnot stand long-term chemical and physical damage.As frequently used modifier with low surface energy,the curing of Polydimethylsiloxane(PDMS)has been severely restricted by time and space.Slippery surface can repel probe liquids but have not the properties of antigraffiti and anti-corrosion.Considering above problems,the article explored the preparation of highly hydrophobic coatings and slippery surface by means of environmental friendly and convenient for large-scale production.Meanwhile,the practical characteristics of these two special wetting materials were studied,including anti-fouling and oil-water separation of the hydrophobic coating and the excellent antifouling,anti-graffiti and anti-corrosion properties of the slippery coating.The details are listed as followed.1.Compared with other micro-nano particles,starch is a renewable resource that is green and environmentally friendly.PDMS as modifier with low surface tension is also non-toxic.Thus potato starch and PDMS were adopted in experiment.At first,hydrophobic coating achieved with the help of spraying technology,which is convenient to produce in large-scale.Afterwards,hot air gun was applied to cure the coating,overcoming the time and space limitations of traditional curing method by oven.The perpared coating can repel daily contaminated liquids such as methyl blue aqueous solution,muddy water,cola and orange juice.The coating can be used to separate oilwater mixture and water-in-oil emulsion,and the separation efficiency is kept above 99% that was measured by ultraviolet absorption method.In addition,the coating has good mechanical stability and chemical durability.Repeated wearing and cyclic bending tests have no influence on the Water Contact Angel(WCA).The coating maintained highly hydrophobicity suffering from long-term immersion in aqueous,acid and salt solution,etc.2.The above prepared highly hydrophobic coating can prevent the impregnation and pollution of aqueous liquids,when it comes to probe liquids with low surface tension coefficient such as ethanol,vegetable oil,and ink,the coating lost its antifouling properties.Thus a kind of slippery surface was prepared by means of crosslinking of PDMS and polydimethylhydrogensiloxane.Thanks to these siloxane polymer chains with low surface energy,the slippery surface had excellent antifouling properties towards liquids with low surface tension coefficient.The layer of flexible molecular chain is firmly grafted on the slippery surface,which is difficult to run off and is conducive to the sliding of probe liquid on it.The whole experiment process is simple and controllable,without special atmosphere and temperature.The prepared coating is highly transparent and its anti-fouling and anti-graffiti effects is great,when organic reagents,water-based dyes,oil-based ink,water-based ink,and viscous oils,etc.are dropped on its surface,all of these liquid will slide off the surface.Also,there is no thick ink will be left on it after the surface suffering graffiti.Compared with the bare metal,the corrosion potential shifted in the positive direction obviously,indicating that anti-corrosion capability of metal was improved due to the coating.Meanwhile,corrosion current density decreased by more than 2 orders of magnitude,which indicated that the slipery coating could seriously reduce the corrosion rate of steel.Additionally,the diameter of the Nyquist curve loop shows that the resistance of the coated steel sheet is much greater than that of bare steel,which indicated that the coating can effectively prevent ions in solution from permeating into steel.In addition,the coating still maintains good antifouling and anti-graffiti performance when it suffering from a series of stability tests including water bath at 60° C for 4 h,oil bath at 120° C for 4 h,heating for 24 h at 250° C,liquid nitrogen freezing for 1 h,UV radiation for 2 h,exposing under sunlight for 20 days,wiping for 250 cycles.