Water- and Heat-Induced Crack-Healing of UCST-Type Poly(acrylamide-co-acrylonitrile) with Intrinsic Controllability and Reversibility

Abstract

Autonomic crack-healing technology has become a common option for reconstructing polymer networks against mechanical degradation, structure mismatch, material fatigue, and even performance failure, but how to precisely and easily trigger this healing process on the crack interfaces is still a huge challenge. Here, we first found an autonomic physicochemical crack-healing behavior featuring intrinsic controllability and reversibility, based on nonionic poly­(acrylamide-co-acrylonitrile) [P­(AAm-co-AN)] with an upper critical solution temperature (UCST). Under the fast synergistic action between extrinsic deionized water and heat, the scratched P­(AAm-co-AN) layer fully returned to the original flat form and was reworked at least five times. Meanwhile, their corresponding optical and mechanical performances also recovered almost 100%. In particular, the intrinsic thermoresponsiveness of P­(AAm-co-AN) takes a leading role in this crack-healing process, in which both interchain transition and topological entanglement come into play. It provides a facile, rapid, precise, green, and autonomic crack-healing strategy for improving polymer durability.

An information encrypted heterogeneous hydrogel with programmable mechanical properties enabled by 3D patterning

“…The LCST of HPC could be regulated accordingly for meeting requirements of different applications, with the commonly used methods being listed in Table S1 (ESI†). Also, considering the high polarity and rheology modification of CNFs, this 3D patterning strategy is believed to be useful for other thermal responsive polymers, such as poly( N -isopropylacrylamide) (PNIPAM), 48 polyethylene glycol (PEG), 49 and their copolymers, 50 which can provide different responsive temperatures for different applications.…”

Thermo-regulating mesoporous semi-rigid metal–organic–polymer frameworks for controllable adsorption and confinement

“…But the resulting topological entanglement will prolong the recovery time or relaxation time of P(AAm-co-AN) chains. 22,23 So limited cooling time of only 1 hour can't make the enlarged pore diameter of MOPFs completely recoverable to the initial state.…”

Thermoresponsive ionogels

“…2K), its derivatives, and copolymers, 79 urea-based derived polymers 80 (Fig. 2L), and poly(acrylamide- co -acrylonitrile) copolymers 81 (Fig. 2M) demonstrate thermal responsiveness due to hydrogen bonding between polymer side groups, similar to LCST polymers.…”