Effect of microphase-separated structure on mechanical toughening of autonomous self-healing tough elastomer in sensor applications

Abstract

Endowing material with self-repairing ability is an effective way to enhance the reliability, durability and functionality of equipment. Self-healing is particularly important for flexible electronic materials and devices. In this paper, the research progress of flexible self-repairing materials and sensors is summarized. In particular, the main problems of how to improve the strength and stiffness of sensors without affecting the self-repairing and electrochemical performance to improve the measurement range and upper limit of mechanical sensors are summarized and further studied. Firstly, the main repair mechanisms of self-healing polymers, including intrinsic self-healing and external aid self-healing, are introduced and discussed. The research progress of self-healing flexible conductive materials, especially the influence of microphase separation technology, is introduced in detail. On this basis, the self-repairing flexible sensors are introduced and discussed, especially the construction method, sensing and self-repairing performance of the self-repairing flexible mechanical sensors. Finally, the existing challenges and solutions for flexible self-repairing materials and sensors are discussed.Intrinsic self-healing elastomers possessing the capability to autonomously repair their structure and functionalities upon mechanical damage have attracted significant attention. However, the preparation of elastomers that combine autonomous self-healing capability and good mechanical properties remain challenging. In the present work, inspired by the strategy of constructing biomimetic microphase-separated structure, we proposed a simple method to realize the mechanically toughen of the polyacrylate elastomer without compromising self-healing performance by using multiphase design with different densities of physical crosslinks formed by carboxyl groups. ABA tri-block acrylate copolymer with pre-designed A and B blocks were prepared via a two-step reversible addition-fragmentation chain transfer radical polymerization (RAFT) and subsequent acid hydrolysis. The resultant elastomer exhibits high fracture energy (88.0 MJ•m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> ), high tensile strength (21.0 MPa) as well as good self-healing performance, which is greatly helpful to expand the range of applications.