Preparation And Study Of Intrinsic Self-healing Amide Elastomers

The intrinsic self-healing polymer material achieves the self-repairing function through reversible intermolecular forces,and has the ability to fully self-heal at room temperature.Current self-healing polymer with hydrogen bonding as the self-healing driving force have excellent self-healing efficiency,but their mechanical properties and performance stability are lower than those of conventional polymer materials limited by the low bonding energy of hydrogen bonds.In this study,ionic interactions with higher bond energy were used to strengthen the intermolecular forces of hydrogen-bonded elastomers,and enhanced intrinsic self-healing elastomers based on the double action of hydrogen bonds and ion bonds were synthesized.Its silica composites were further prepared.The aggregate structure,mechanical properties,thermal properties,viscoelasticity,dielectric properties,and water resistance properties of the material were studied,then the mechanism and effect of the ionic bond and hydrogen bond during the healing process were analyzed in detail.Single hydrogen-bonded intrinsic self-healing amide elastomer SE,and hydrogen-ionic interacting intrinsic self-healing amide elastomer SEI were prepared separately.The SE shows lower strength as a weaker elastomer.However,SEI,which assembles by both metal carboxylate ion bond and hydrogen bond,is characterized by higher strength and rigidity elastomer material.Compare to SE,the elastic modulus of SEI at 20% deformation increased by 1157%,the tensile strength increased by 177%,and the elongation at break decreased by 53%,reaching 13.45 MPa,5.15 MPa and 313% respectively.Through tensile behavior,glass transition,dielectric properties and TEM microstructure,the two-phase structure of the material was further confirmed,in which the metal carboxylate hard phase dispersed in the polyamide soft phase scaled around 10 nm.Through the self-healing test of SEI material under room temperature,the reversible bonding mechanism of hydrogen and ionic interactions in the intrinsic healing process was analyzed,and the healing model of the material was constructed.The ionic bond has fast response,but the proportion of ionic bonds that can be re-bonded is limited;while the hydrogen bond has a high proportion of re-bonding but required a longer healing time.The self-healing material based on the double action of ionic bonds and hydrogen bonds combines the advantages of two kinds of acting forces.The stiffness of SEI is recovered quickly,and after 4 hours,the tensile modulus of the material could reach 13.5 MPa which is the same as original sample.When the healing time was 24 hours,both the rigidity and elasticity of the network were restored,and the tensile strength and elongation at break of the material achieve 82% and 96% of the original sample respectively.A series of silica-modified self-healing materials were prepared by blending SEI as a matrix material and silica as filler.It is concluded that modified nano-silica(KSi)has the best modification effect.Adding 10 phr KSi will maximize the mechanical properties of SEI,the elastic modulus will further increase by 146% at 20% deformation,the tensile strength will increase by 95%,and the elongation at break will decrease by 18%,to 33.10 MPa,10.04 MPa and 256% respectively which achieve the strength of traditional rubber material.From the normal-temperature tensile behavior of the healing sample,the tensile strength of the 24 h healing material can reach 7.78 MPa,and the 20% deformation tensile modulus is 25.01 MPa.The KSi filled SEI material can maintain good intrinsic self-healing properties while enhancing the mechanical properties.The composite material has the capability of self-healing at room temperature.