Preparation And Properties Of Superhydrophobic Surfaces Based On Dihydrazide Derivative Molecular Gels

In recent years,superhydrophobic materials have been applied in daily life and industrial productions,due to their potential applications in self-cleaning,anti-contamination,anti-corrosive,oil–water separation,underwater drag reduction and so on,which has stimulated the research enthusiasm of domestic and foreign researchers.However,the preparation of artificial superhydrophobic materials still has many shortcomings,such as complex preparation process,high production cost and poor mechanical durability.Therefore,it is of great research significance to explore the preparation of a kind of superhydrophobic material with a simple preparation process,low production cost and high mechanical durability.In this paper,we firstly use cheap1,4-bis[(3,4-bisoctyloxyphenyl)hydrozide]phenylene(BPH-8)as the raw materials to successfully prepare a series of superhydrophobic surface coatings through its molecular gel(molecular self-organization).Then,the friction resistance of the coating surface was improved by introducing metal or epoxy resin to compound with the coating.Finally,a super hydrophobic composite coating with simple preparation method and practical application value was obtained.The main research contents and results are as follows:1.Using low-molecular weight organic gelator(BPH-8)as the raw material,the high-quality uniform and dense superhydrophobic surface was successfully prepared in one step by controlling the volume ratio of ethanol(Et OH)and tetrahydrofuran(THF)to control the gelation rate and microscopic morphology.With the increase of the THF content in the mixed solvents,the water contact angle of the xerogel surfaces changed from superhydrophobic(150.8°)to superhydrophobic(164.5°)and then to hydrophobic(115.5°),and the water sliding angle of the xerogel surfaces changed from high adhesion to low adhesion and then to high adhesion,indicating that the surface wettability changed from Wenzel state to Cassie-Baxter state and then to Wenzel state.By scanning electron microscope(SEM)and atomic force microscope(AFM)to analyze the xerogels microstructure,we found that the microscopic morphology of the xerogel surfaces gradually changed from the micro-nano hierarchical structure to the porous structure with the increase of THF content in the mixture,and the roughness also showed a trend of first increasing and then decreasing,which well explained the change of wettability of xerogel surfaces with the increase of THF content in the mixture.Through XRD and gelation formation kinetic analysis,we confirmed that BPH-8 molecules self-assembled to form a layered structure during the aggregation process and presented a linear one-dimensional growth model of J aggregation in the Et OH/THF mixed solvent.2.To improve wear resistance of the BPH-8/ETOH superhydrophobic organic coating,we obtained a kind of organometallic composite coating by coating a layer of metal or metal oxide on the surface of the BPH-8/ETOH superhydrophobic organic coating and studied its surface wettability and wear resistance.The results showed that the water static contact angle of the BPH-8/Et OH coating was about 162°;The surface of the composite coating coated with Al₂O₃ on BPH-8/Et OH xergeol loseed the superhydrophobicity;the water static contact angle of the Al/BPH-8/Et OH composite coating could be maintained in the superhydrophobic state,but it decreased with the increase of the aluminum film thickness;the static water contact angle of the composite coating coated with Ag on BPH-8/Et OH xergeol still remained at about 162°.The reason might be that the surface energy of Al₂O₃ and Al is higher than that of Ag,causing Al₂O₃ and Al to spread on the surface of the organic superhydrophobic coating to enhance the interaction between the surface of the composite coating and water,which ultimately leaded to a decrease of the water static contact angle.In addition,compared to the BPH-8/Et OH coating,the wear resistance of the composite coating coated with metal Al or Ag has been enhanced and the effect was the same.3.In order to enhance the wear resistance of the superhydrophobic organic coating,we also tried to introduce epoxy resin to prepare two kinds of organic polymer superhydrophobic composite coatings and studied their surface wettability and wear resistance.The results showed that the water contact angle of the surface of two kinds of organic polymer superhydrophobic composite coatings obtained by the gelation method and the powder method was maintained at about 162°.In addition,two kinds of organic polymer superhydrophobic composite coatings obtained by the two methods were worn with 150 mesh,180 mesh,220 mesh,240 mesh,320 mesh and 400 mesh sandpaper for multiple cycles.The surface wettability of the composite coatings could still be maintained the superhydrophobic state,showing high-strength wear resistance and strong environmental applicability.