Radically Modified Polyisoprene toward a Multifunctional Rubber Moiety with Self-Healable and Recyclable Properties

The successful development of tough cis 1,4-polyisoprene (cis-PI) with excellent room-temperature self-healing capability can expand its application scope from merely typical rubber production materials to wearable electronic devices. However, the involvement of additional chemical cross-linking processes mostly by the sulfur vulcanization technique to produce sufficient mechanical properties usually comes at the expense of self-healing capability and nonrecyclability. As an alternative to eliminating additional vulcanization processes and minimizing material usage for simplicity, our group offers a straightforward one-step method by adopting the peroxide-cross-linked principle to initiate the radical state that directly incorporates two monomers, namely, N-vinyl carbazole (NVC) with a rigid characteristic and 2-[[(butylamino)carbonyl]oxy]ethyl acrylate (BACO) with a soft characteristic, into the cis-PI main chain as the rubber matrix. Through appropriate ratio content of NVC and BACO, the radically modified PI (rm-PI) can achieve splendid mechanical properties (tensile stress of 2.91 MPa, a maximum strain of 1087%, and toughness of 25.27 MJ·m–3), notch insensitivity, and excellent fast recoverability that remains at 96% of initial dissipated energy after 25 cycles continuously. The synergistic effect between the dynamic H-bonds from BACO and π–π stacking from NVC, coupled with high polymer chain diffusion, are responsible for the high autonomous self-healing efficiency of >90% even after a deadly cut. In addition, the efficient recyclability of rm-PI through the modest procedure of dissolution and remodeling can be achieved without relying on extreme external factors, due to the profitable rm-PI linear structure without any additional covalent cross-linking process. These outcomes are expected to promote a viable approach for developing a multifeature modified cis-PI.