Polyurethane (PU) is a versatile polymer used in a wide range of applications. Recently, imparting PU with self-healing properties has attracted much interest to improve the product durability. The self-healing mechanism conceivably occurs through the existence of dynamic reversible bonds over a specific temperature range. The present study investigates the self-healing properties of 1,4:3,6-dianhydrohexitol-based PUs prepared from a prepolymer of poly(tetra-methylene ether glycol) and 4,4'-methylenebis(phenyl isocyanate) with different chain extenders (isosorbide or isomannide). PU with the conventional chain extender 1,4-butanediol was prepared for comparison. The urethane bonds in 1,4:3,6-dianhydrohexitol-based PUs were thermally reversible (as confirmed by the generation of isocyanate peaks observed by Fourier transform infrared spectroscopy) at mildly elevated temperatures and the PUs showed good mechanical properties. Especially the isosorbide-based polyurethane showed potential self-healing ability under mild heat treatment, as observed in reprocessing tests. It is inferred that isosorbide, bio-based bicyclic diol, can be employed as an efficient chain extender of polyurethane prepolymers to improve self-healing properties of polyurethane elastomers via reversible features of the urethane bonds.
Keywords: bio-based polyurethane; isomannide; isosorbide; self-healable; thermo-reversible.