Shanghai Engineering Research Center of Nano-Biomaterials and Regenerative Medicine, Research Base of Textile Materials for Flexible Electronics and Biomedical Applications of China Textile Engineering Society,State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai 201600, China
Multiple hydrogen bonds are a kind of supramolecular interactions with high bonding strength and dynamic reversibility, which can form physical crosslinking networks in linear polymers to improve the mechanical strength of materials and endow them with good selfhealing ability. Polyurethane with multiple hydrogen bond physical crosslinking structure was synthesized from polytetrahydrofuran, hexamethylene diisocyanate and 2,4-diamino-6hydroxypyrimidine. When the molar ratios of polytetrahydrofuran and chain extender 2,4-diamino-6-hydroxypyrimidine were 7∶3 and 5∶5, supramolecular polyurethane elastomers with mechanical strength and self-healing ability were obtained. The chemical structure and basic properties were characterized by 1H-NMR, IR, gel permeation chromatography, differential scanning calorimetry and rheological test. Comparison of the mechanical and self-healing properties of two groups of elastomers revealed that the different composition altered the physical crosslinking density of multiple hydrogen bonds and the mobility of the molecular chain. When the mole ratio of polytetrahydrofuran and chain extender was 7∶3, material had higher elongation at break (1280%); when the molar ratio was 5∶5, the material had better deformation recovery ability during cyclic stretching, and the stress relaxation was slower; both groups of elastomers showed definite selfhealing ability at 60 ℃.