Highly Adherent Intelligent Protective Elastomers With Impact Hardening Effect

As a kind of protective material,impact hardening material has always been one of the hot spots in research.It mainly has a broad application space in sports protection,military and police protection,material packaging ang all.Related research mainly focuses on energy absorption,self-healing and material functionalization.However,when materials are used in the field of flexible wearables,it is difficult to balance impact hardening characteristics and elastic energy return to improve wearing comfort.At the same time,impact hardening materials are usually applied by sizing and other methods to make the material stick to the protected matrix,in high and low temperature,underwater and even acid and alkali conditions,protective materials usually produce adhesion failure and other problems,causing many unnecessary troubles.Therefore,starting from the structural design of the flexible main chain,this paper combines dynamic and steady-state dual crosslinking mechanism to prepare intelligent protective elastomers with impact hardening characteristics,self-healing properties and high adhesion properties.How to improve the adhesion performance of intelligent protective materials while ensuring impact hardening characteristics,self-healing and other characteristics,and realizing the protection intelligence of impact hardening elastomers is the focus of this paper.The specific research conclusions are as follows:1.The hydroxyl-terminated polydimethylsiloxane（PDMS-OH）was used as the linear flexible main chain,and the boron-oxygen dynamic bond in trimethoxyboron oxide hexacyclo（TMOB）was used as the dynamic crosslinking center as the dynamic chemical network.The polydimethylsiloxane（PDMS）as the steady-state chemical center,a series of dual nerwork polydimethylsiloxane-impact hardening polymer elastomers（PDMS-IHP）with good external sensitivity characteristics and high mechanical properties were synthesized.The self-healing efficiency of the material can reach about 80%within 48 h,and the energy absorption efficiency is as high as 85%at the impact speed of 4.43 m s^-1.2.On the basis of PDMS-IHP,poly-2-（（（（butylamino）carbonyl）oxo）butyl methacrylate）（PBM）was prepared by radical polymerization as an adhesion functional component,and multiple network impact hardening elastomers（PDMS-AI）with adhesion were prepared by in-situ crosslinking and compounding.The self-healing efficiency of PDMS-AI is over 88%,and the transparency is greater than 90%,and the energy absorption efficiency can reach 78%at the impact velocity of 4.43 m s^-1.At the same time,PDMS-AI has excellent interface adhesion performance,and the adhesion strength of the material on the glass substrate can reach 198 k Pa,which is nearly 100 times higher than that of ordinary PDMS materials.3.On the basis of PDMS-IHP,2-amino-4-hydroxy-6-methylpyrimidine（UPy）is introduced on the linear flexible backbone end hydroxyl group of IHP,and a series of double-network impact hardening elastomers（PDMS-UI）with good external sensitivity characteristics and high adhesion properties are synthesized by using the quadruple hydrogen bond in UPy.PDMS-UI material has self-healing ability in air and water,and the healing efficiency in air and water after 5 h is more than 90%.The adhesion strength on different substrates exceeds 150 k Pa,and it has the ability to adhesion and transfer adhesion multiple times.At the same time,PDMS-UI material has good soft and hard conversion ability,and the energy absorption rate is as high as 75.23%at the impact speed of 4.43 m s^-1.