Novel disulfide-containing diols: synthesis and application in self-healing fluorescent polyurethane elastomers

Abstract

The synthesis of polyurethane elastomers with repair abilities and robust mechanical properties under mild conditions remain a great challenge. Numerous studies have shown that dynamic disulfide bonds are the important chemical chain unit of polyurethane with self-healing properties. Therefore, the synthesis of diols containing a disulfide bond chain unit is the key for achieving polyurethane with self-healing properties. In this study, three kinds of hydroxyl-capping diol fluorescent molecules containing disulfide were synthesized from 2,2′-dithiobisbenzoic acid (DTSA) with glycol (EG), 1,4-butanediol (BDO) or 1,6-hexanediol (HDO) via esterification. The structures and properties of the synthesized aromatic disulfide diol and the derived disulfide-containing self-healing fluorescent polyurethane (SFPU) were characterized using proton nuclear magnetic resonance (¹H NMR and ¹³C NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), small-angle X-ray scattering (SAXS), dynamic mechanical analysis (DMA), and other techniques. The results demonstrated the successful synthesis of diols containing aromatic disulfide bonds. The self-healing rate of polyurethane elastomers, with aromatic disulfide diols introduced as hard segments, was approximately 61.50% at 20 °C. Polyurethane elastomers exhibited excellent mechanical properties and demonstrated fluorescence. These novel self-healing fluorescent polyurethane elastomers can be widely used in industries such as building, clothing, furniture, medical materials, armaments, and packaging. This research study will have some guiding significance in expanding the application of self-healing fluorescent polyurethane.