Surface Interface Design And Properties Of Extrinsic Self-repairing Materials With Stimulation Response

Hybrid polymer coatings have been widely utilized in the fields of electronic devices,buildings,traffic transportation,and so on,due to the characteristics of easily processing,highly strength,lightweight,and facile functionalization.However,it is unavoidable to be destroyed by local damage or microcracks during the processes of molding and using for these coatings.Inspired by the spontaneous repair of biological damage in nature,researchers are committed to developing self-healing materials.This work aims at developing novel extrinsic self-healing materials to improve the self-healing capabilities.Herein,organic/inorganic UV-shielding materials were introduced into the shell of a single UV-triggered self-healing microcapsule to construct extrinsic self-healing materials with both high-efficiency UV-shielding and UV-induced self-healing abilities.To improve the self-healing ability,an extrinsic amphiphilic polymer modified supramolecular self-healing materials with good wettability were also designed.The organic coating embedded with supramolecular polymers exhibited outstanding mechanical property and multiple reversible heat-initiated self-healing ability based on dynamic reversible chemical bonds and non-covalent interactions of supramolecular structure.Zn O and Ce O₂ nanoparticles with UV absorption ability were in-situ deposited into the mesoporous structure of the photoinitiated self-healing Si O₂ microcapsule shells for aerospace coatings to obtain self-healing and UV-shielding single Si O₂/Zn O and Si O₂/Ce O₂ microcapsules,respectively.Zn O and Ce O₂ nanoparticles exhibited strong UV absorption to endow the microcapsules with excellent UV-shielding ability and to effectively protecting the active photoinitiator in the core of microcapsule.Meanwhile,the coating containing Si O₂/Zn O microcapsules and Si O₂/Ce O₂ microcapsules after UV-aging still exhibit good self-healing ability to effectively avoid the issue that UV irradiation penetrates the microcapsule shell and causes the failure of healing agents in the capsule core before healing behaviors during the long-term service life.To construct a self-healing microcapsule material with both good UV light shielding performance and excellent organic matrix compatibility,polydopamine（PDA）was deposited into the mesopores of Si O₂ microcapsules to obtain UV-initiated Si O₂/PDA microcapsules.The PDA shell layer endows Si O₂/PDA hybrid microcapsules with good UV-shielding performance.Also,the benzene ring and polar groups in PDA improved the compatibility between Si O₂/PDA hybrid microcapsules and epoxy resin matrix,enhancing the responsiveness of microcapsules to microcracks.Si O₂/PDA microcapsules aged under UV light for 192 h still preserved outstanding self-healing ability for epoxy resin coatings.To enhance the UV-shielding ability of microcapsules,resorcinol formaldehyde resin（RF）containing donor-acceptor（D-A）couple was introduced into the mesoporous structure of the Si O₂ microcapsule shell to obtain Si O₂@RF hybrid microcapsules with an improved UV-shielding property and excellent compatibility.The quinone and benzene monomers in RF resin form D-A couples with strong UV absorption.In addition,similar molecular structure between the RF resin and the epoxy resin matrix endows microcapsules with good compatibility.The Si O₂@RF microcapsules aged for 48 days under UV irradiation still maintained excellent self-healing ability.Besides,the deposition of D-A type 3-aminophenol formaldehyde（APF）and hydroquinone formaldehyde（HF）resins onto Si O₂ microcapsules could also significantly improve the UV-shielding ability of UV-initiated self-healing microcapsules.Amphiphilic polymer was utilized to regulate the compatibility of TA-DIB-Fe supramolecular polymers with epoxy coatings,constructing a heat-initiated extrinsic self-healing coating with reversible multiple self-healing capabilities and mechanical properties based on reversible dynamic chemical bonds and non-covalent interactions.The existence of amphiphilic polymer F127 makes supramolecular polymers uniformly distributed in epoxy resin in the form of microphase separation.Due to the dynamic covalent disulfide bonds,non-covalent hydrogen bonds,and iron-carboxylate coordination bonds in the TA-DIB-Fe copolymer network,the coating achieved multiple reversible self-healing for the morphology and mechanical property,with self-repairing efficiencies of106%,104.7%,and 106.5%for 1st,2nd,and 3rd self-healing,respectively.