Active photo-thermal self-healing of shape memory polyurethanes

Abstract

Structural health monitoring (SHM) has received significant interest over the past decade and has led to the development of a wide variety of sensors and signal processing techniques to determine the presence of changes or damage in a structural system. The topic has attracted significant attention due to the safety and performance enhancing benefits as well as the potential lifesaving capabilities offered by the technology. While the resulting systems are capable of sensing their surrounding structural and environmental conditions, few methods exist for using the information to autonomously react and repair or protect the system. One of the major challenges in the future implementation of SHM systems is their coupling with materials that can react to the damage to heal themselves and return to normal function. The coupling of self-healing materials with SHM has the potential to significantly prolong the lifetime of structural systems and extend the required inspection intervals. In the present study, an optical fiber based self-healing system composed of mendable polyurethanes based on the thermally reversible Diels–Alder (DA) reaction is developed. Inspired by health monitoring techniques, active photo-thermal sensing and actuation is achieved using infrared laser light passing through an optical fiber and a thermal power sensor to detect the presence of cracking in the structure. Healing is triggered as the crack propagates through the polymer and fractures the embedded optical fiber. Through a feedback loop, the detected power drop by the sensor is utilized as a signal to heat the cracked area and stimulate the shape memory effect of the polyurethane and the retro-DA reaction. The healing performance results indicate that this novel integrated system can be effectively employed to monitor the incidence of damage and actively heal a crack in the polymer.

Fast and Efficient Electric‐Triggered Self‐Healing Shape Memory of CNTs@rGO Enhanced PCLPLA Copolymer

“…However, to date most of these polymers are only thermo‐sensitive, which cannot be precisely controlled and locally responsive, so they dissatisfy the growing practical requirements . Hence, it is expected to not only explore more channel stimuli‐responsive smart polymers, but also to design multifunctional materials including shape memory and self‐healing behaviors …”

Synergistic effects of zwitterionic segments and a silane coupling agent on zwitterionic shape memory polyurethanes

“…[1][2][3] Until now, various stimuli, such as light, heat, moisture, and pH value, have been used to adjust the macroscopic properties of SMPs. [4][5][6] In comparison with shape memory alloys and shape memory ceramics, SMPs have advantages of light-weight, good biocompatibility, high deformability, and easy adjustment of shape recovery temperature.…”

Flexible Self‐Repairing Materials for Wearable Sensing Applications: Elastomers and Hydrogels

“…Dynamic covalent self-healing flexible materials mainly include reversible acylhydrazone bond, [31][32][33][34] disulfide bond, [35][36][37][38][39][40][41] Diels-Alder reaction, [42][43][44][45][46][47][48][49][50] CON and urea bond. [51][52][53][54][55][56][57] In 2012, Bao et al prepared a flexible pressure/bending sensor with self-healing.…”

“…Dynamic covalent self‐healing flexible materials mainly include reversible acylhydrazone bond, [ 31–34 ] disulfide bond, [ 35–41 ] Diels–Alder reaction, [ 42–50 ] CON and urea bond. [ 51–57 ] In 2012, Bao et al.…”