Self-Healing and Adhesive Supersoft Materials Derived from Dynamically Cross-Linked Bottlebrush Polymers for Flexible Sensors

Multifunctional bottlebrush polymer supersoft materials are highly desirable for the development of next-generation flexible electronic devices. Herein, we report a facile strategy for the fabrication of bottlebrush polymer supersoft materials integrated with self-healing and adhesive functionalities. These are achieved by the first fabrication of the bottlebrush poly(n-butyl acrylate) (PnBA) via combining atom transfer radical polymerization with ring-opening metathesis polymerization and subsequent formation of dynamically cross-linked networks via "click" thiol-bromo reaction between Br end groups of PnBA side chains and dithiol-containing boronic ester cross-linker. Owing to the unique architecture and the reversible boron ester bonds, the unique bottlebrush architecture and fast bond-reforming kinetics of boron ester bonds impart the resultant materials with supersoftness with a shear modulus as low as 5 kPa and high self-healing efficiency over 90%. Moreover, owing to the extremely low glass transition temperature of PnBA segments, they also display strong adhesiveness to many substrates. The as-prepared strain sensors show an excellent ability to detect a large range of strains from an ultralow strain of 0.1% to a large strain of 100%. This work has provided a facile and promising approach to the development of multifunctional supersoft materials, which hold great potential as functional sensors for flexible electronics.