A Self-Healing Elastomer with Extremely High Toughness Achieved by Acylsemicarbazide Hydrogen Bonding and Cu~(2+)-Neocuproine Coordination Interactions

Elastomers with high mechanical toughness can guarantee their durability during service life.Self-healing ability,as well as recyclability,can also extend the life of materials and save the consuming cost of the materials.Many efforts have been dedicated to promoting the mechanical toughness as well as the self-healing capability of elastomers at the same time,while it remains a challenge to balance the trade-off between the above properties in one system.Herein we proposed a molecular design driven by dual interactions of acylsemicarbazide hydrogen bonding and Cu~(2+)-neocuproine coordination simultaneously.By introducing the reversible multiple hydrogen bonds and strong coordination bonds,we successfully fabricated an extremely tough and self-healing elastomer.The elastomer can achieve an impressive top-notch toughness of 491 MJ/m~3.Furthermore,it boasted rapid elastic restorability within 10 min and outstanding crack tolerance with high fracture energy(152.6kJ/m~2).Benefiting from the combination of dynamic interactions,the material was able to self-repair under 80℃conveniently and could be reprocessed to restore the exceptional mechanical properties.

Microstructures and mechanical properties of Ta-Nb-Zr-Ti-Al refractory high entropy alloys with varying Ta/Ti ratios

The refractory high entropy alloys(RHEAs)containing disordered body-centered cubic(BCC)and ordered BCC(B2)structures often exhibit high strength but low ductility at room temperature,even in the compressive tests.In this study,(Ta_(25-x)Nb_(25)Zr_(25)Ti_(25+x))95Al_(5)(x=0,5,10)RHEAs are fabricated to investigate the compositional dependence of the microstructures and mechanical properties.All the three alloys exhibit a single BCC structure at the as-cast and solution-treated states,while the basket weave-like microstructures consisting of cuboidal and strip-like phases are formed after aging at 600°C.The microstructure of the aged alloys is sensitive to the compositions:only disordered BCC1+BCC2 dual phases are observed in the(Ta_(25)Nb_(25)Zr_(25)Ti_(25))_(95)Al_(5)alloy;additional B2 phases are formed by replacing 5 at%Ta with Ti;a complex microstructure containing BCC1+BCC2+B2+Omega phases are identified in the(Ta_(15)Nb_(25)Zr_(25)Ti_(35))_(95)Al_(5)alloy.Although replacing Ta with Ti results in a reduction of compressive yield strength from 1762 to 1243 MPa,the fracture strain is greatly enhanced from 7.3 to 44.3%,indicating that the strength-ductility balance can be tuned to a large extent in this RHEA system.