Bio-based healable non-isocyanate polyurethanes
The scientists Jincheng Dong,a Binyuan Liu,a, b Huining Ding,a Junbin Shi,b Ning Liu,b Bin Dai,b and Il Kimc from the aHebei University of Technology, Tianjin, China, the bShihezi University, Shihezi, China, and the cPusan National University, Busan, Korea, have synthesised a series of isocyanate-free polyurethanes (NIPUs), showing an intrinsic thermo-healing performance, from sustainable vegetable oil-based cyclic carbonates and bio-based amines.
The bio-based contents of the NIPUs are higher than 78 %. Their thermo-mechanical and self-healing performances are tailored simply by varying the feed ratios of the amines employed.
The biomass linoleic acid dimer-based diamine plays a positive role in maintaining the higher thermal stability and good elasticity of the prepared NIPUs, the cycloaliphatic isophorone diamine contributes to high tensile strength, and cysteine-derived disulfide-containing cystamine (CA) enhances the self-healing efficiency.
The combination of intrinsic hydrogen bonds existed in the NIPU matrix with the dynamic exchange reactions of disulfide bonds and the enhanced flexibility of NIPU networks results in 98.1 % self-healing efficiency at 25 °C. The contributions of disulfide bonds and hydrogen bonds to the healing efficiency were estimated by adjusting the composition of NIPUs, showing that the contribution of disulfide bonds to the healing ability is about 45.3 % even at a low amount of CA (6.0 wt%).
The study “Bio-based healable non-isocyanate polyurethanes driven by the cooperation of disulfide and hydrogen bonds” has been published in the journal Polymer Chemistry (2020, 11, p. 7524) from the Royal Society of Chemistry (RSC).