Polypyrrole-functionalized g-C3N4 for rheological, combustion and self-healing properties of thermoplastic polyurethane

It is a challenge to manufacture multifunctional, two-dimensional, nanosized additive for polymer by a simple and universal method. Herein, a phytic acid-doped polypyrrole shell was successfully grown on the surface of exfoliated g-C3N4 nanosheets (CNPPy) by an in-situ polymerization method. CNPPy was directly incorporated into thermoplastic polyurethane (TPU) to prepare multifunctional TPU nanocomposites with near-infrared (NIR) induced self-healing properties. Rheological analysis showed that the combination of carbon nitride and polypyrrole formed a stable network in the TPU matrix. Compared to pure TPU, the incorporation of 3 wt% CNPPy into TPU exhibited 43.4% lower peak heat release rate and 53.4% lower peak smoke release rate. In addition, the mechanical performance of the CNPPy-TPU nanocomposite remain basically unchanged. Meanwhile, the tensile strength of a cut composite was restored to 31.3% in 45 s via NIR. The strategy of in-situ polymerization of conjugated polymers on the surface of two-dimensional nanosheets enables polyurethane composites with both improved rheological and self-healing properties and broadens the application field of two-dimensional nanosheets.