Ultra-Tough, Strong, and Defect-Tolerant Elastomers with Self-Healing and Intelligent-Responsive Abilities.

Mechanical strength, toughness, and defect tolerance are usually exclusive in most artificial materials. Herein, inspired by many biomaterials that overcome this tradeoff by integrating soft and hard ingredients through elaborate structural designs, we report a facile latex-assembly method to fabricate ultra-tough, strong, and defect-tolerant elastomers. The elastomers are featured by a microscopic inverse opal-mimetic rigid skeleton of dynamically cross-linked chitosan and a continuous soft matrix of vulcanized natural rubber. Such structural design enables the load-bearing capability, sacrificial property, and self-healing ability of the skeleton, the stress redistribution and extensibility of the matrix, and the stiffness variation between hard and soft ingredients, thereby imparting the elastomers with outstanding mechanical strength and defect tolerance, as well as extremely high toughness of 122 KJ m-2, which is even higher than that of the current state-of-the-art titanium alloys. Moreover, the elastomers show prominent humidity sensitivity due to the hydrophilic nature of the chitosan skeleton. Harnessing these advantages, we fabricate a walking robot triggered by humidity variation and shoes that are able to regulate temperature and humidity. The concept of designing a rigid sacrificial skeleton within a soft continuous matrix on the microscale is quite general, enabling the development of high-performance and intelligent materials for emerging applications.

Synergistic effect of CB and GO/CNT hybrid fillers on the mechanical properties and fatigue behavior of NR composites.

In this paper, graphene oxide (GO) and carbon nanotube (CNT) hybrid fillers were used to replace partial carbon black (CB), and GO/CNT/CB/NR composites were prepared with excellent crack growth resistance, low heat build-up and superior mechanical properties. Mechanical testing revealed a significant synergistic reinforcement between GO/CNT and CB in NR composites. The improved dispersion of GO/CNT hybrid fillers and CB in the NR matrix was characterized by transmission electron microscopy (TEM). Through the fatigue test, the GO/CNT/CB/NR composites showed excellent fatigue crack growth resistance and low heat build-up compared to CB/NR composites. These properties provide the NR composites with better applications in industry.