Synergistic Enhancement Of Ammonia Ester-Based Self-healing Polymer Materials By Double Reponse Of Thermal Reversible Bonds

Elastomer and epoxy resin,such as three-dimensional network due to the excellent physical and chemical properties are widely used in various fields,but when in the process of serving under the strong physical and mechanical effect,the internal structure of micro cracks caused by fatigue,and thus easily,cause mechanical properties gradually recession,not fully play the role of itself and cause a waste of resources around the world.Therefore,self-healing materials emerge at the historic moment and become a research hotspot in the 21 st century.The most commonly used self-healing mechanism is intrinsically self-healing mechanism.By introducing reversible bonds into the cross-linking network,the self-healing function of materials can be realized under external stimulation.This repair method does not need to inject healing agent into the matrix and can realize multiple repairs at the same position,so it has attracted widespread attention.At present,most of the intrinsic self-healing properties of materials reported in the literature are achieved by single-response reversible bonds such as Diels-Alder bond,ester bond,disulfide bond and hydrogen bond,which have high response temperature,limited repair efficiency and long heating time.This paper constructs the ammonia ester dual response self-healing elastomer key/hydrogen bond and ammonia ester bond/ester key dual response selfhealing epoxy resin polymer,the thermal reversible ammonia ester bond is introduced into the elastomer and epoxy crosslinking network,the use of ammonia ester bond efficient reversible and sensitivity to temperature,constructed based on ammonia ester bond two high density dynamic key crosslinking network system,Through the occurrence of reversible bond reversible reaction,the flow of molecular chain segment is realized,and the self-healing function of materials is realized.Compared with the single response system,the reversible bond dual response system can respond quickly in a short time to realize the material self-healing,and the self-healing effect is relatively ideal.The main job and results of this paper are as follows:(1)EUHDI and EUMDI were synthesized by the reaction of Eugenol with aliphatic hexamethylene diisocyanate(HDI)and aromatic diphenylmethane diisocyanate(MDI).In this paper,infrared tracking method was used to investigate the release and reclosure behavior of Urethane based monomers EUHDI and EUMDI.The experimental results show that Urethane based monomers have the characteristics of high temperature release and low temperature reclosure.Four Urethane based elastomers(EUHDI/3SH,EUHDI/4SH,EUMDI/3SH,EUMDI/4SH)with different cross-linking densities were prepared by the thiol-ene click reaction using urethane based monomers EUHDI and EUMDI as prepolymers and three or four functional mercaptans.The three-dimensional network contains high-density urethane bonds,and a large number of hydrogen bonds can be formed between the molecular chains in the network.Therefore,the Urethane bond/hydrogen bond double response thermal reversible self-healing crosslinking network is constructed.Its properties were characterized by DSC,DMA,swelling test,self-healing test and degradability test.The results show that Urethane based elastomers have excellent self-healing properties at high temperature.After heat treatment at 150? for 30min,the surface scratches of EUHDI/3SH and EUHDI/4SH elastomers can be repaired by 100%.The mechanical properties of EUHDI/3SH and EUHDI/4SH can be restored to 90.5%and 76.6%of the original spline respectively.Due to the influence of steric hindrance and crosslinking density.The elastic mechanical properties of EUMDI/3SH and EUMDI/4SH can be restored to 70.7%and 44.7%of the original spline respectively.It is proved that the Urethane based elastomer has degradability through degradability characterization,which is helpful to environmental protection.(2)In the system with high glass transition temperature(Tg),the thermal response of hydrogen bond is limited.In order to obtain highly efficient thermally reversible epoxy resin,the Urethane/ester bond strategy is used to construct the dual thermal response system.Urethane based epoxy resin was synthesized by oxidation reaction using Urethane based monomer EUHDI as prepolymer.It is structure was characterized by IR,NMR and epoxy value.The infrared tracking method was used to explore the unsealing behavior of Urethane based epoxy resin.The results showed that the Urethane based epoxy resin had the unsealing performance.The best unsealing temperature is 150?and the unsealing reached equilibrium in 30 min.the maximum degree of unsealing was 31.6%.With 1,2-cyclohexanedicarboxylic anhydride was used as a crosslinking agent to crosslink Urethane based epoxy resin.The crosslinking network of urethane based/ester based high-density dynamic reversible bond epoxy resin was obtained.The crosslinking network was characterized by DMA,infrared tracking,swelling test,self-healing test and degradability test.The results showed that the crosslinking network had the properties of unsealing and re sealing,and passed through the ester under the condition of thermal stimulation(150?)The mechanical modulus of the cut-off spline can be restored to 67.5%of the original spline after heat treatment for 30 min,the mechanical strength can be restored to 27.2%of the original value,which indicates that the repair effect of reversible bond double response self-healing material is better than that of single response self-healing material.It is proved that the crosslinking network of Urethane based epoxy resin is degradable,which is helpful for environmental protection.