Preparation And Properties Of Self-healing Silicone Elastomer

Silicon polymer materials are widely used in the fields of biomaterials,wearable devices,intelligent coatings,energy storage materials and robotics because of their highly designable molecular structure and flexible reaction characteristics.However,the materials will inevitably be damaged by external mechanical,physical or chemical factors in the process of use,resulting in local damage,or tiny cracks,which will shorten the service life and cause safety risks.Therefore,self-healing silicone elastomer has an important application prospect.In this paper,biomolecules and metal ions were introduced into polydimethylsiloxane to form a self-healing crosslinking networks with variety of dynamic reversible bonds.Then,by adjusting the molecular weight of polydimethylsiloxane and the content of metal ions.We were systematically discussed the mechanical properties,self-healing properties,thermal stability and dynamic mechanical properties of the self-healing silicone elastomer,and studied application in metal anticorrosive coating of the silicone elastomer.The details were as follows:1.The crosslinking network of silicone elastomers(IA-PDMS)based on covalent bond and hydrogen bond was prepared by condensation of aminopropyl-terminated polydimethylsiloxane(A-PDMS)and biotic itaconic acid(IA).The molecular structure of IA-PDMS was characterized by FTIR and ~1H NMR.The mechanical property test shows that the tensile strength of IA-PDMS can reach 448 kPa.The self-healing test show that the self-healing efficiency of IA-PDMS can reach 77%by hydrogen bond interaction at 100℃for 12 h.TGA shows that IA-PDMS has good thermal stability.Its thermal decomposition occurs at about 300℃,and almost completely decomposition at about 600℃.DMA shows that the storage modulus(G’)of IA-PDMS increases first and then decreases with the increase of ammonia value of A-PDMS,and glass transition temperature decreases from-104.6℃ to-108.1℃.2.The prepolymer TA-PDMS was synthesized by aminopropyl terminated polydimethylsiloxane(A-PDMS)and thioctic acid(TA).Then,the self-healing silicone elastomer TA-PDMS-Py-Fe was successfully prepared by crosslinking 2,6-dimethylpyridine(Py)with ferric chloride.The dynamic reversible bond network based on hydrogen bond,dynamic disulfide bond and metal coordination bond was constructed in TA-PDMS-Py-Fe.The molecular structures of TA-PDMS and TA-PDMS-Py-Fe were characterized by FTIR and ~1H NMR.SEM and EDS showed that TA-PDMS-Py-Fe had good dispersibility.The mechanical properties test shows that the tensile strength of TA-PDMS and TA-PDMS-Py-Fe can reach 304.1 kPa and 464.5 kPa respectively.The self-healing performance test shows that the self-healing efficiency of TA-PDMS-Py-Fe is up to 90.2%through three kinds of dynamic reversible bond interaction at 120℃for 12 hours.TGA shows that the initial thermal decomposition of TA-PDMS-Py-Fe is about 400℃,and the maximum decomposition temperature is about 700℃.DMA shows that the storage modulus(G’)of TA-PDMS-Py-Fe increased with the increase of metal ions,and glass transition temperature increases from-106.9℃ to-99.2℃.The tests of metal corrosion resistance and bonding mechanical properties show that TA-PDMS-Py-Fe has strong adhesion to smooth surface due to the cooperation of hydrogen bond and metal complex,and TA-PDMS-Py-Fe has good metal corrosion resistance.