Preparation And Application Of Superhydrophobic And Self-healing Polysiloxane Cross-linked By Dynamic Bonds

Superhydrophobic material refers to the material with water contact angle greater than150^o(WCA>150^o)and sliding angle less than 10^o(SA<10^o).It has important applications in self-cleaning,anti-icing,drag reduction,oil-water separation and other aspects.However,due to the structural factors of the superhydrophobic material,it is easy to produce damage under the action of external force,leading to the decline of performance.Inspired by nature,the concept of self-healing is introduced into superhydrophobic materials to extend the service life.The current major repair of superhydrophobic performance way has two kinds:chemical damage(chemical oxidation and degradation)and physical damage repair(crack,pinhole and nick),at present most self-healing superhydrophobic materials for are based on a kind of injury repair and most need to external stimuli(light,heat,humidity,microwave,etc.),but the superhydrophobic materials during long time use is often faced with multiple complex uncertain damage condition,a single,plus the conditions needed to repair greatly limits the practical application.In this paper,the reversible dynamic bond network is introduced into the superhydrophobic flexible silicone elastomer materials.On the one hand,the physical damage can be repaired at room temperature by improving the activity of polymer chain and the bond exchange of dynamic bonds.On the other hand,dynamic bond exchange can accelerate the migration of low surface energy compounds and realize rapid room temperature repair of chemical damage,so as to obtain multiple rapid room temperature self-healing superhydrophobic flexible materials,which lays a foundation for the development of self-cleaning superhydrophobic coatings with excellent durability.The main work of this paper is divided into the following two parts:The tensile strength and elongation of Zn-IC-PDMS were 0.23±0.05 MPa,232±10%,and the mechanical repair was achieved at room temperature.The repair rate was 73±2%after 24h.Subsequently,a superhydrophobic elastomer(SiO₂/PS/Zn-IC-PDMS)with dual micro/nano structure was constructed by spraying micron PS and nanometer silica on the surface of Zn-IC-PDMS.The elastomer has excellent superhydrophobic properties,with contact Angle of155^o and slidung Angle of 3^o,and has excellent self-cleaning ability for ink,milk,coffee and dust.After 30 cycles of friction,the contact Angle is still greater than 150^o and the rolling Angle is less than 10^o,showing excellent durability.The hydrophobic properties of SiO₂/PS/Zn-IC-PDMS superhydrophobic coating decreased significantly after scratch damage(CA=140^o,SA=75^o).The superhydrophobic properties of the metal coordination bond exchange were quickly repaired(CA=154^o,SA=?10^o)at room temperature without external stimulation for 20 min.After multiple scratch-repair cycles,the contact Angle can still be greater than 150^o.Imine/coordination double-crosslinked organosilicate elastomers(imine-BZn-PDMS)were synthesized and prepared to further improve the mechanical properties and self-healing properties of elastomers.The tensile strength of the elastomer is increased to 0.51 MPa,the toughness is 0.67 MJ/m³,and the recovery rate is 94%.A two-layer dynamic bond elastomer structure was proposed,that is,imine-bzn-pdms/SiO₂ coating was constructed on the surface of imine-bzn-pdms coating.The prepared elastomer(HB-imine-BZn-pdms)not only possessed superhydrophobic properties,with a contact angle of 154^o and a sliding angle of 5^o,but also showed good wear resistance,and the contact Angle remained above 150^o after 40cycles of grinding by sandpaper.In addition,the superhydrophobic properties of the superhydrophobic elastomer were not significantly affected after multiple tensile cycles.Double dynamic key lower polymer structure dynamic key polymer provides physical damage repair,and the upper formation of super hydrophobic polymer performance,at the same time,through the key and the chain exchange between layer and layer effect,HB-imine-BZn-PDMS at room temperature can be realized triple repair:mechanical properties,chemical and physical injury(scratches and pinhole)damage repair.The contact Angle of physical damage,such as scratches and needles,can be restored to more than 150^o at room temperature for 20 min.After oxygen ion etching,HB-imine-BZn-PDMS showed rapid(40 min)room temperature self-healing ability,which is better than most self-healing superhydrophobic materials,and has a potential application prospect in the fields of wearable electronics and electronic skin.