Journal of Colloid and Interface Science, Vol.559, 152-161, 2020
Room temperature readily self-healing polymer via rationally designing molecular chain and crosslinking bond for flexible electrical sensor
Mechanically tough polymers with excellent room temperature self-healing capacity have aroused strong interest in soft electronics, electronic skins and flexible energy storage devices. However, achieving such polymers remains a challenge due to tardy diffusion dynamics. Herein, a robust and readily self-healing polymer, which is synthesized by one-pot polymerization among 2,4'-tolylene diisocyanate, isophorone diisocyanate, and poly(oxy-1,4-butanediyl), is achieved through reasonably tuning the hardness of the molecular segment and the strength of the dynamic crosslinking bond. The poly(oxy-1,4-butanediy1) that act as a soft segment can effectively avoid the microphase separation, enabling rapid chain mobility of the polymer at the room temperature. Furthermore, the dual H-bonding from 2,4'-tolylene diisocyanate segment acting as a relatively strong crosslinking bond contributes to high mechanical strength, while the weaker single H-bonding from isophorone diisocyanate segment can efficiently dissipate strain energy by bond rupture, endowing the polymer with rapid room temperature self-healing ability. Featuring state-of-the-art of robust stress strength (approximate to 1.3 MPa), high self-healing efficiency (97% within 6 h), and large tensile strain (approximate to 2100%), the resulting polymers are used for the fabrication of stretchable and self-healable electrical sensor, which can be employed to monitor a variety of physiological activities in real time. The described strategy is promising and universal for healable materials, displaying great potential for developing soft electronics. (C) 2019 Elsevier Inc. All rights reserved.