Micro Nano Structure Design And Construction Of Superhydrophobic Surface Of Rubber Material

Superhydrophobic surface has excellent characteristics of self-cleaning,anti-pollution,anti-snow cover and other,and shows great potential in transportation,construction,medicine and other fields.But there are some problems at present,firstly,the preparation process is complex and the production cost is high;secondly,the superhydrophobic products are mostly based on hard materials such as metals and plastics,or they are membrane structures or coatings,which have low strength and poor mechanical stability.Therefore,developing a superhydrophobic surface with simple preparation process,flexibility and good mechanical stability has great significance for the large-scale application of superhydrophobic surface.Based on the sol-gel technology,a flexible and durable rubber based superhydrophobic surface was prepared by in situ micro nano rough structure on the surface of the swollen vulcanized rubber.The effects of sol-gel process on hydrophobicity and micromorphology were systematically studied,and the self-cleaning and mechanical stability of superhydrophobic materials were characterized.Firstly,the SiO₂ micro nano composite structure was prepared in situ on the surface of sulfurized natural rubber（NR）with n-butyl amine as the swelling agent and tetraethyl orthosilicate（TEOS）as the precursor of sol-gel reaction.After being modified by stearic acid（SA）,the highest water contact angle（WCA）was 153.5°.Scanning electron microscopy（SEM）showed that the surface of the sample was densely packed with irregular spherical SiO₂ particles of micro and nano scale to form a uniform and compact hydrophobic layer.The essence of the reaction is that TEOS swollen into rubber undergoes hydrolytic condensation reaction catalyzed by n-butylamine to produce SiO₂ in situ.Secondly,the superhydrophobic surface of MVQ-SiO₂ was prepared by sol-gel process using the cured methyl vinyl silicone rubber（MVQ）as the substrate.The sample was swelled in n-butylamine aqueous solution for 3 h,then reacted in TEOS for 2.5 h.After two-step modification of SA,the excess SA was removed by immersion in isopropanol（IPA）.The maximum WCA was 162°.SEM showed that the surface of the sample was composed of many SiO₂ microspheres with a diameter of about 1μm,and the surface of each microsphere was self-assembled with a dense"nano-hill"bulge,forming a lotus leaf structure.The sample has excellent drainage,self-cleaning and mechanical stability.Finally,MVQ-ZnO superhydrophobic surface was prepared by sol-gel process using sulfurized MVQ as substrate.When the sample was swelled in n-butylamine aqueous solution for 3 h and reacted in Zn（NO₃）₂/ethanol solution for 4 h at 60℃,the excess SA was removed by IPA immersion after SA two-step modification,and the WCA of the sample reached 158°.SEM showed that the surface of the sample was composed of many three-dimensional micro-nano-ZnO flower-like structures,in which the micro-sized ZnO flower-ball was composed of multi-layer nano-flake petals.Superhydrophobic surface has excellent wear resistance,water impact resistance,peeling resistance and ultrasonic vibration,bending deformation resistance,pressure resistance,medium resistance and other properties.This preparation method of the rubber-based superhydrophobic material is simple and easy to operate,and possesses many advantages such as mechanical stability,flexibility and fluorine-free.It lays a theoretical and practical foundation for the large-scale application of the superhydrophobic material.