Preparation And Properties Of Self-healing Superhydrophobic Surfaces Based On Shape Memory Effect

Superhydrophobic surfaces have attracted tremendous attention over the past decades in both academic and industrial areas due to their emerging applications including antifouling,antibacterial,oil/water separation,etc.However,many superhydrophobic surfaces lose easily their superhydrophobicity due to suffering from mechanical scraping,physical abrasion or chemical corrosion which limit their practical applications.Imparting superhydrophobic surfaces with self-healing properties is an effect way to solve this problem.In this research,as coating materials,shape memory polymers were used to construct micro-nano tier roughness structure on the substrate.Due to the shape memory effect of the polymer coatings,the as-prepared samples could recover the crushed micro-nano structures to make the surface return to be superhydrophobic,showing healing of superhydrophobicity.(1)A superhydrophobic coating with self-healing property was prepared by depositing shape memory epoxy resin(EP)and polydimethylsiloxane(PDMS)on glass surface via aerosol-assisted layer-by-layer chemical vapor deposition(AA-LbL-CVD).The surface morphology of the coating was examined using field emission scanning electron microscope(SEM).Elemental analysis of the coating surface was conducted by X-ray photoelectron spectroscopy(XPS).Contact angles(CAs)and sliding angles(SAs)were measured using a video optical contact angle system.Investigations were conducted of the effects of deposition temperature,total volume,time,and volume ratio of Vepoxy:VPDMS on the surface hydrophobicity of the coating.Durabilities of the as-obtained superhydrophobic coatings were investigated.It was found that the obtained superhydrophobic coating showed excellent chemical robustness even after exposure to different chemicals,such as acid,base or salt solution.Meanwhile,the coating surface maintained superhydrophobicity after 2 m sandpaper abrasion,250 cycles double sided type peeling,or long-time exposure to UV irradiation.Importantly,the coating could repair its superhydrophobicity after heating at 85? for 3 min when the coating lost its superhydrophobicity due to the damage of roughness structure of the prepared coating.(2)Self-healing superhydrophobic coating which could repair both roughness structure and low surface energy was fabricated by depositing the mixture of epoxy resin precursor,PDMS and ODA on glass substrate using AACVD method.The surface morphology of the coating was examined using SEM.Elemental analysis of the coating surface was conducted by XPS.CAs and SAs were measured using a video optical contact angle system.The effects of the amount of ODA,deposition temperature and total volume on the surface hydrophobicity of the coating were studied.The as-obtained superhydrophobic coatings showed excellent chemical robustness even after exposure to different chemicals,such as acid,base,or salt solution.Importantly,the coating surfaces maintained superhydrophobicity after 2 m sandpaper abrasion,250 cycles double sided type peeling,as well as long time exposure to UV irradiation.Also,the obtained coating could repair not only its roughness structure but also surface energy under heating condition when the surface lost its superhydrophobicity due to the damage of roughness structure or lost of low surface energy.(3)Self-healing superhydrophobic coating on textile which could repair both roughness structure and low surface energy was fabricated by dip-coating of fabrics in the mixture of epoxy resin precursor,PDMS and ODA.The surface morphology of the coating was examined using SEM.Elemental analysis of the coating surface was conducted by XPS.CAs and SAs were measured using a video optical contact angle system.The effects of PDMS concentration,ODA concentration and dipping time on the hydrophobicity of the coating were studied.The results showed that the superhydrophobicity of the as-fabricated coating possessed remarkable durability against different pH solutions and exhibited excellent resistance to repeated machine washing or severe abrasion damaging.Moreover,the superhydrophobicity of the coating showed remarkable self-healing ability against both chemical and physical damages when the surface lost its superhydrophobicity upon heating due to the damage of roughness structure or low surface energy.In conclusion,shape memory polymer combined with low surface energy material was used to construct micro-nano tier roughness structure to realize the healing or double healing of the roughness structure or/and low surface energy property,utilizing the memory function of the shape memory polymer on the physical microstructure and the molecular chain flipping of the low surface energy polymer as well as the migration of the low surface energy small molecules.This work paves a new avenue for the study of durable and stable superhydrophobic surfaces,and lays a foundation for scientific research and application practice,which promotes the progress of superhydrophobic surfaces towards practical applications.