Preparation And Properties Of Dual Cross-linking Silicone Self-healing Materials With Strong And Weak Coordination Bonds

Silicone elastomers exhibit lots of unique properties,such as biocompatibility,high and low temperature resistance and corrosion resistance.Silicone elastomers have been widely used in aerospace,electronic equipment,biomedicine and transporation and will not be lack in our lives.However,the Materials such as elastomers produce will inevitably be damaged during static or dynamic stretching,extrusion,shearing,torsion and other mechanical effects,which can seriously shorten their lifetime and increases the cost of material replacement.Therefore,self-healing materials have important application prospects.At present,most silicone self-healing materials cannot balance mechanical properties and self-healing efficiency.In fact,in most supramolecular designs,an inherent compromise exists between self-healing capability and mechanical properties.Generally,strong interchain interactions result in higher strength and toughness but slower healing dynamics that precludes healing;weak interchain interactions afford good healing efficiency but yield inferior mechanical performance,Therefore,it is very important to explore silicone self-healing materials with relatively high mechanical properties and self-healing efficiency.Carboxyl-modified silicone is typical reactive silicone oil.Because of its high reactivity,carboxyl-modified silicone is widely used in functional materials and high-performance materials.In this study,mercaptosuccinic acid modified polysiloxane(PDMS-g-MS)was prepared via Carboxylic acid groups were grafted via thiol-ene reaction,and then the polymer can be cross-linked by ionic hydrogen bonds between the reactivity carboxylic acid group of PDMS-g-MS and the amine groups of the cross-linkers.Different cross-linkers such as tris(2-aminoethyl)amine?p-Phenylenediamine and ethylenediamine and their dosages were investigated for the mechanical properties.Meanwhile,the healable property of the elastomer was investigated.In addition,in order to further improve the mechanical properties of the silicone materials.The dual-network silicone elastomer was crosslinked with trimethylolpropane tris(3-mercaptopropionic)and the ionic hydrogen bonds formed from the reaction of carboxyl and amino.The dual cross-linking network improved the mechanical strength significantly,and provided a new crosslink system of silicone elastomer.Meanwhile,the elastomer showed the thermoplasticity and shape memory properties.In addition,inspired by the energy dissipation mechanism and the recoverability of sacrificial bonds,a dual-dynamic network design of high-performance elastomer in which weaker hydrogen bonds and stronger coordination have been engineered into silicone materials.Under healing at 80? for 24 h,the healed elastomer regains excellent mechanical properties(tensile strength of 2.4 MPa).