The Fabrications And Properties Of The Biomimetic Superhydrophobic Materials Based On Polydimethylsiloxane

Superhydrophobic surface is a kind of bio-inspired materials inspired from the self-cleaning phenomenon,which usually has high contact angle?>150°?and low sliding angle?<10°?.It has been found that the rough structure and low surface energy substance on the surfaces determined the superhydrophobicity.Polydimethylsiloxane?PDMS?is a kind of desired low-surface-energy hydrophobic material with approximate 22 mN/m surface tension at room temperature.Rough treatments could improve the PDMS surfaces from hydrophobic to superhydrophobic.Superhydrophobic material modified by PDMS is fluoride-free,environmentally friendly,low-cost,and accessible,which is different from others modified by expensive fluorosilane.In addition,PDMS is a kind of adhesive,which also provide the adhesion among the particles and substrate to some degree.In this dissertation,PDMS was introduced to the fabrication of superhydrophobic materials with more simple and efficient method,and we emphasized the durability to improve their potential applications.The main researches of this dissertation were shown as follows:1.We applied a new aluminum template with initially etched by HCl solution to fabricate microstep structure,and then immersed into boiling water to obtain nanoflake structure on the microsteps.Six polymers including acrylonitrile-butadiene-styrene?ABS?,polycarbonate?PC?,PDMS,polymethylmethacrylate?PMMA?,polystyrene?PS?,and polyurethane?PU?were replicated the micro/nano multiple structure of the aluminum substrate,and the rough polymer surfaces were obtained after the dissolution of aluminum.After being immersed into low-surface-energy solutions for modification,those surfaces presented superhydrophobic,improved oleophobic,and good stabiliby.The reasons of the good stability were as follows:the introduced nano structures improved the wettability of the polymer surfaces as compared to the surface only with microstrure;higher microstep's structure would protect the structures of the low microsteps and nanoflakes.2.With HCl solution etching and subsequent boiling water treatment,hierarchical structure was displayed on the aluminum substrates.PDMS solution was spin-coated on the substrates,and the superhydrophobicity was emerged on the surfaces after the curing procedure.The surfaces were robust and thermal recovery.When underwent sparingly volatile peanut oil contamination or severely weight abrasion,the structures and chemical substances of the surfaces damaged,leading to the loss of superhydrophobicity.PDMS would partially decompose and the low surface energy decomposition would absorb on the damaged structures after the simple calcination,leading to the recovery of their superhydrophobicity.The thermally self-healing ability improved their durability to some extent.3.PDMS liquid was placed in the crucible with a glass slide on it.Transparent superhydrophobic surface was obtained on the glass slide substrates with one-step calcination process,and the residue powder in the crucible was superhydrophobic as well.The transparent superhydrophobic surface could repel aqua regia and saturated NaOH solutions with strong corrosion.It was robust and self-cleaning both in air and oil environment.In addition,the superwettability was changed by regulating the heating time and temperature.According to the characters of the structure and chemical composition,the main reasons for the tunable superwettability were as follows:for one,the number and diameter of deposited PDMS soot have influence on the surface structure;for another,the decomposed degree of PDMS impacted the low-surface-energy substances on the surface.4.The flame retardent ZnSn?OH?₆ particles were pressed into the concentrated PDMS solution on a glass substrate.After the curing treatment,superhydrophobic coating was obtained.PDMS not only provides the low-surface-energy modification to realize superhydrophobicity,but also enhances the bonding forces among substrate and particles,leading to the excellent durability of the coating.The decompositions of ZnSn?OH?₆ particles would form a compact carburizated layer,which would resist the air to protect the coating during the flame processes.The ZnSn?OH?₆ particles could endow the flame retardency to the coating,which widens the applications of this superhydrophobic coating.The superhydrophobic coating demonstrated a great self-cleaning ability in air condition,in oil condition,and on the oil contaminated surfaces in air condition.In addition,the coating could be covered on several substrates to realize superhydrophobicity.5.PDMS and ZnSn?OH?₆ particles were mixed completely,and then spray-coated on a filter paper to obtain superhydrophobicity.After adding a pristine filter paper on the superhydrophobic one,the membrane with two pieces of filter paper was achieved.When the emulsion passed from the superhydrophilic filter paper with high surface energy to the superhydrophobic filter paper with low surface energy,the surface ener gy gradient was formed,generating an imbalanced force.The added force would elevate the separation,which plays a significant role in the increased separation efficiency and separation cycles,and the stabilized emulsion with high surfactant concentratio n was also separated successfully.Double pieces of filter paper would narrow the pores,which also good for the separation.In addition,the pristine filter paper could be replaced easily.It was easier to separate surfactant stabilized emulsion by simply importing a pristine paper.Moreover,the ZnSn?OH?₆ particles endowed the flame retardency to the superhydrophobic filter paper as well.