Impact of synthesis parameters on the properties of polymer/MXene nanocomposites

Abstract

MXenes are a relatively new class of 2D nanomaterials with promising properties. The functional groups on the surface of the nanosheets play a vital role in interacting with other materials, especially in nanocomposites. Biocompatibility, admirable mechanical properties, and thermal stability are the most significant properties of poly(dimethylsiloxane)-based polyurethanes (PU). They are highly convenient for applications in electronic devices and implants. In this study, the MXene content was 1 wt. % for two series and 0.5 wt. % for the other two series, while the soft segment content was 50 wt. % for all the series. The nanocomposites were obtained using an in-situ polymerization method. The timing of adding the MXene nanoparticles to the reaction mixture was also varied to examine the changes in the physico-mechanical properties of the nanocomposites. Differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and tensile tests were conducted to analyze the properties of the resulting materials. The glass transition temperature is highest for the series in which MXenes are added in the first phase of polyaddition after the solvation of MDI, while the series with 0.5 wt.% MXene added later into the reaction exhibit two transitions. SEM images revealed uneven distribution and agglomeration of MXene nanoflakes when added into the siloxane prepolymer. The tensile test indicated that the series with 0.5 wt. % nanoflakes have significantly lower Young's modulus and tensile strength. The distribution of nanoparticles and surface morphology are strongly influenced by the timing of adding the MXene dispersion into the reaction mixture, as well as the nanoparticle content.