Self-Healing Supramolecular Polyurethane Elastomers Based on Multiple Hydrogen Bonds
Multiple hydrogen bonds are a kind of supramolecular interactions with high bonding strength and dynamic re-versibility,which can form physical cross-linking networks in linear polymers to improve the mechanical strength of materials and endow them with good self-healing ability.Polyurethane with multiple hydrogen bond physical crosslinking structure was synthesized from polytetrahydrofuran,hexamethylene diisocyanate and 2,4-diamino-6-hydroxypyrimidine.When the molar ratios of polytetrahydrofuran and chain extender 2,4-diamino-6-hydroxypyrimidine were 7∶3 and 5∶5,supramolecular polyu-rethane elastomers with mechanical strength and self-healing ability were obtained.The chemical structure and basic proper-ties were characterized by 1 H-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 compo-sition altered the physical crosslinking density of multiple hydrogen bonds and the mobility of the molecular chain.When the mole ratio of polytetrahydrofuran and chain ex-tender 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 elasto-mers showed definite self-healing ability at 60℃.
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