Synthesis, Characterization and Thermal Properties of Intrinsic Self‐Healing Polyurethane Nanocomposites

Abstract A hybrid thermo‐reversible crosslinking polyurethane nanocomposite containing 0.5, 1, and 2 wt.% of nano‐silica was prepared with three intrinsic self‐healing bonds (reversible covalent bonds supported by intrinsic hydrogen bonds and dangling chains). Owing to the introduction of pseudo‐tannin and polyester diol that could form phenol‐urethane networks and using nano‐silica that causes dangling chains and hydrogen bonds, the prepared polyurethanes are capable of being reversed at 110 °C and rejoin at low temperatures. Thermoset self‐healing polyurethane nanocomposites are prepared from pseudo‐tannin, nano‐silica, and a urethane‐based prepolymer. The investigations of chemical structure, self‐healing behavior, and cross‐link network are carried out by Fourier Transform Infrared Spectroscopy (FTIR), Differential Scanning Calorimetry (DSC) technique, and swelling test. dissociation of phenolic urethane at 110 °C was confirmed by temperature variable FTIR. By swelling test, it was found that the self‐healing polyurethane nanocomposites with 0.5 wt.% of nano‐silica have the most hard‐domain, gel content, and crosslink density in the samples. DSC technique shows that polyurethane samples have two heat transfer transitions (dangling chains and self‐healing). Thermogravimetric analysis (TGA) findings show that nanocomposites decompose at elevated temperatures than neat PU, and the rate of degradation diminishes as silica content increases.