Thermal Stability and Flammability Studies of MXene-Organic Hybrid Polystyrene Nanocomposites.

Polystyrene (PS) is widely used in the plastics industry, but the application range of PS is limited due to its inherently high flammability. A variety of two-dimensional (2D) nanomaterials have been reported to impart excellent flame retardancy to polymeric materials. In this study, a 2D nanomaterial MXene-organic hybrid (O-TiC) was applied to PS as a nanofiller. Firstly, the MXene nanosheets were prepared by acid etching, intercalation, and delamination of bulk MAX (TiAlC) material. These exfoliated MXene nanosheets were then functionalized using a cationic surfactant to improve the dispersibility in DMF. Even with a small loading of functionalized O-TiC (e.g., 2 wt%), the resulting PS nanocomposite (PS/O-TiC) showed good thermal stability and lower flammability evidenced by thermogravimetric analysis (TGA) and pyrolysis-combustion flow calorimetry (PCFC). The peak heat release rate (pHRR) was significantly reduced by 32% compared to the neat PS sample. In addition, we observed that the temperature at pHRR (T) shifted to a higher temperature by 22 °C. By comparing the TGA and PCFC results between the PS/MAX and different weight ratios of PS/O-TiC nanocomposites, the thermal stability and 2D thermal- and mass-transfer barrier effect of MXene-organic hybrid nanosheets were revealed to play essential roles in delaying the polymer degradation.