The Construction And Performance Of High-stability Super-hydrophobic Silicone Rubber Composite Material Based On UV Curing

Superhydrophobic materials have attracted much attention because of their promising applications in water-proofing,self-cleaning,anticorrosion,drag reduction,and oil-water separation.To prepare the superhydrophobic surfaces,researchers have made great effort to construct elaborate rough structures by various bionic methods including self-assembling,electro-spinning,dip-coating,chemical vapor deposition,and gel-sol coating,which expand the applications of superhydrophobic materials.However,there are some problems with these methods,they mainly focus on the following two aspects:First,the preparation steps are cumbersome and time-consuming,the efficiency is low,the curing process often requires high temperature,etc.Second,prepared superhydrophobic surfaces are relatively fragile,they are easy to wear and fall under mechanical loads,and the repair process after damage is complicated and time consuming.Therefore,exploring the super-hydrophobic surface with simple preparation process and stable anti-wetting property is a research difficulty and focus in the field of superhydrophobic materials.UV(ultraviolet)curing reaction has the characteristics of rapid and room temperature curing,which provides feasible for efficient and rapid preparation of superhydrophobic materials at room temperature.Therefore,this thesis develops methods to prepare the silicone rubber-based robust superhydrophobic materials based on UV curing technology.We developed a fast method to prepare a robust and stretchable superhydrophobic surface by UV cross-linking of the superhydrophobic coating onto the underlying substrate.Upon one-step UV exposure,polyurethane acrylate(PUA)can be cured to a stretchable elastomeric substrate whose surface remains rich reactive functionalities(C=C)due to the oxygen inhibition.The oxygen-inhibited layer(uncured PUA)of the substrate can covalently bond to superhydrophobic coating under further UV exposure and results in the strong interface adhesion between the coating and the substrate.The peel strength of the coating on the uncured side of the PUA substrate(2.3 MPa)is much larger than that of the coating on the cured side of the PUA substrate(0.8 MPa).As expected,the superhydrophobic coating covalent-bonded to the PUA substrate(18-cycle abrasion)shows better abrasion-resistance than that physically adhered to the substrate(less than 8-cycle abrasion).Besides,the resulting superhydrophobic surface can withstand 1000-cycle stretching-releasing(strain of 200%)without losing its original superhydrophobicity and self-cleaning ability.Furthermore,PUA can also be used as a transition layer for various substrates to build robust superhydrophobic surfaces.In order to overcome the problem of difficult to repair quickly after the superhydrophobic coating is damaged,a robust and flexible bulk superhydrophobic film was successfully prepared by rapid thiol-ene photopolymerization of a PDMS/silica/cyclohexane suspension followed by solvent evaporation.A homogeneous translucence suspension was rapidly cured under UV light to form a gel system,fixing the hydrophobic particles to their respective original sites by the polymer molecular chains.As the gel dried,a bulk superhydrophobic film with sufficiently rough surface and porous internal structure was fomied.The solvent content plays an important role in tuning the cross-linking degree and the porous structure of the polymer matrix(binder),both of which significantly affect the mechanical properties of the resultant superhydrophobic film.With the optimized solvent/polymer mass ratio(15:1),the film shows high abrasion resistance and good mechanical strength.As expected,the coating can keep its superhydrophobicity under bending,twisting and stretching.Besides,the superhydrophobic surface can withstand 500-cycle abrasion without losing its original superhydrophobicity.The silica particles and porous structure form a self-similar and hierarchical structure across the film bulk,which is repetitively exposed to the surface by abrasion and thus maintains durable superhydrophobicity.Taking advantage of these regenerative characteristics,a damaged superhydrophobic surface can be rapidly recovered by sanding treatment without the use of healing agents.Thus,our superhydrophobic film can be applied to various flexible substrates(e.g.,functional fabrics)for durable waterproof and self-cleaning functions.Endowing the bulk superhydrophobic film with good thermal conductivity can expand its application range.The suspension consisting of hydrophobic Al2O3 particles/PDMS/cyclohexane was rapidly prepared into a flexible thermally conductive bulk superhydrophobic film using the "UV Curing+Solvent Evaporation" method.When the composite film is stretched to 100%,the distance between the surface mastoids only slightly increases,the overall roughness is almost constant,and the superhydrophobicity is remained.After undergoing 1000 stretching-relaxation cycle experiments(strain of 100%),the liquid-solid contact between water and film resides in the Cassie state.In the sandpaper abrasion test,a self-similar superhydrophobic structure was continuously exposed on the surface of the composite film,which could ensure long-lasting superhydrophobicity and has no obvious decay of its CA and SA after 600-cycle abrasion tests.The superhydrophobic surface structure of the composite film has excellent water repellency,under normal temperature,the anti-wetting time is greater than 12 h under water pressure of 1 m.