Bis(2-hydroxyethyl) Terephthalate-Modified TiCT/Graphene Nanohybrids as Three-Dimensional Functional Chain Extenders for Polyurethane Composite Films with Strain-Sensing and Conductive Properties.

Incorporation of functional nanofillers can unlock the potential of polymers as advanced materials. Herein, single-layered and three-dimensional reduced graphene oxide (rGO)/TiCT (B-rGO@TiCT) nanohybrids were constructed using bis(2-hydroxyethyl) terephthalate (BHET) as a coupling agent between rGO and TiCT through covalent and hydrogen bonds. It is found that BHET can not only resist the weak oxidization of TiCT to some degree but also prevent the self-stacking of TiCT and rGO sheets. Then, B-rGO@TiCT was used as a functional nanofiller and three-dimensional chain extender for preparing the waterborne polyurethane (WPU) nanocomposite through in situ polymerization. Compared with WPU nanocomposites with an equivalent amount of TiCT/rGO@TiCT, although containing an equivalent amount of BHET, WPU/B-rGO@TiCT nanocomposites show significantly improved performance. For example, 5.66 wt % of B-rGO@TiCT endows WPU with a high tensile strength of 36.0 MPa (improved by 380%), thermal conductivity of 0.697 W·m·K, electrical conductivity of 1.69 × 10 S/m (enhanced by 39 times), good strain-sensing behavior, electromagnetic interference (EMI)-shielding performance of 49.5 dB in the X-band, and excellent thermal stability. Therefore, the construction of rGO@TiCT nanohybrids with the aid of chain extenders may unlock new possibilities of polyurethane as smart materials.