Self‐Healing Polyurethanes with Shape Recovery

Abstract

Two new thermoresponsive self‐healing polyurethanes (1DA1T and 1.5DA1T) based on the Diels–Alder (DA) reaction between furan and maleimide moieties are developed that use the shape‐memory effect to bring crack faces into intimate contact such that healing can take place. Unlike other self‐healing polymers, these polymers do not require external forces to close cracks but rather they use the shape‐memory effect to autonomously close the crack. Both polyurethanes have a stable polymer structure and comparable mechanical properties to commercial epoxies. A differential scanning calorimeter is employed to check the glass transition temperature of the polymers as well as the DA and retro‐DA (rDA) reaction temperatures. These DA and rDA reactions are confirmed with variable‐temperature proton nuclear magnetic resonance. Healing efficiency is calculated using a measurement of the failure load from compact tension testing. The results show that the shape‐memory effect can replace external forces to close two crack surfaces and the DA reaction can be repeatedly employed to heal the cracks.

Scaffolded Thermally Remendable Hybrid Polymer Networks

“…Other researchers have performed healing cycles on step-growth DA polymers at elevated temperatures below T gel , to improve the kinetics of the forward and reverse reactions and encourage bond exchange in the disrupted regions of the material. [ 13,[23][24][25] This approach, however, has limited benefi ts in healing interfaces that are no longer in direct contact with one another, and samples often must be held together to bring the edges suffi ciently close to enable healing to take place.…”

Segmented linear shape memory polyurethanes with thermoreversible Diels-Alder coupling: Effects of polycaprolactone molecular weight and diisocyanate type

“…The other advantages of this reaction are as follows: both DA and retro-DA (rDA) reaction undergo without catalyst and no byproducts forms. The DA adducts form by the reaction of a conjugated diene and a dienophile at a temperature range from 20 to 90°C and can be cleaved via rDA reaction above 120°C [23][24][25][26][27]. The retro reaction, i.e.…”

Tuning chain extender structure to prepare high-performance thermoplastic polyurethane elastomers

“…This is the rst thermoplastic polyurethane elastomers with such high thermostability and excellent mechanical properties, compared to the present reported PUs. 7,12,19,50 Furthermore, the comprehensive performance of such pure polyurethane is even superior to many polyurethane-based composite polymers.…”

“…Therefore, there is a huge consumption of PUs in the global plastic application market at high growth rate. [2][3][4][5] Recently it also shows interesting applications in self-healing materials, [6][7][8] stimuliresponsive materials, [9][10][11][12] and exible conductive materials. 13 Meanwhile, concerns about the poor heat resistance of PUs limit their further applications.…”