Bis(2-hydroxyethyl) Terephthalate-Modified Ti3C2T x /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)/Ti3C2T x (B-rGO@Ti3C2T x ) nanohybrids were constructed using bis­(2-hydroxyethyl) terephthalate (BHET) as a coupling agent between rGO and Ti3C2T x through covalent and hydrogen bonds. It is found that BHET can not only resist the weak oxidization of Ti3C2T x to some degree but also prevent the self-stacking of Ti3C2T x and rGO sheets. Then, B-rGO@Ti3C2T x 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 Ti3C2T x /rGO@Ti3C2T x , although containing an equivalent amount of BHET, WPU/B-rGO@Ti3C2T x nanocomposites show significantly improved performance. For example, 5.66 wt % of B-rGO@Ti3C2T x endows WPU with a high tensile strength of 36.0 MPa (improved by 380%), thermal conductivity of 0.697 W·m–1·K–1, electrical conductivity of 1.69 × 10–2 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@Ti3C2T x nanohybrids with the aid of chain extenders may unlock new possibilities of polyurethane as smart materials.