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

Abstract

Multifunctional bottlebrush polymer supersoft materials are highly desirable for the development of nextgeneration 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.

Bottlebrush Networks: A Primer for Advanced Architectures

“…These length-scales were determined via our LengthScale app. methods: (1) brush polymerization via ROMP followed by post polymerization crosslinking (covalent [8,[71][72][73][74][75][76][77] or supramolecular [78][79][80][81][82] ) or (2) in situ crosslinking via ROMP with telechelic macromonomers. [9,10,56,[83][84][85] These ROMP BBNs have been synthesized with a wide variety of side chains including poly (ethylene glycol), [56,71,72,83] polycaprolactone or polymethylcaprolactone, [72,73,[78][79][80][81] poly (lactic acid), [80] poly (dimethylsiloxane), [8][9][10]72,76,83,85] poly (n-butyl acrylate), [82,84] polystyrene [77] and poly (methyl methacrylate).…”

“…methods: (1) brush polymerization via ROMP followed by post polymerization crosslinking (covalent [8,[71][72][73][74][75][76][77] or supramolecular [78][79][80][81][82] ) or (2) in situ crosslinking via ROMP with telechelic macromonomers. [9,10,56,[83][84][85] These ROMP BBNs have been synthesized with a wide variety of side chains including poly (ethylene glycol), [56,71,72,83] polycaprolactone or polymethylcaprolactone, [72,73,[78][79][80][81] poly (lactic acid), [80] poly (dimethylsiloxane), [8][9][10]72,76,83,85] poly (n-butyl acrylate), [82,84] polystyrene [77] and poly (methyl methacrylate). [74] Despite this accessibility, ROMP suffers from several crucial limitations including: (1) the need for solvent during polymerization, (2) sensitivity to solvent type/conditions, and (3) limited backbone monomers which exhibit the ringstrain necessary for ROMP to be viable.…”

Alternating Graft Copolymer Carrying PLA Graft Chains at Every Other Unit: Sequence Impacts on Crystallization Behaviors

“…Development of living polymerization has allowed synthesis of various well-defined polymer architectures showing advanced structure-oriented properties/functions. − In particular, graft copolymers or bottlebrush polymers have attracted attention because of the densely attached chains on the backbone. − They can be created via three approaches: “grafting-from,” “grafting-through,” and “grafting-to.” The molecular design of monomers/initiators and the combination of some controlled polymerizations and/or click-chemistry has allowed construction of complicated architectures leading to unique self-assembly characters. − Potential features have been reported toward material applications …”