Large-scale production of simultaneously exfoliated and Functionalized Mxenes as promising flame retardant for polyurethane

The low yield of MXenes nanosheets and its poor interfacial compatibility with polymer matrix have been an unavoidable obstruction for the fabrication of related polymer nanocomposites. Here, we reported a facile and large-scale route for the simultaneous organic modification and exfoliation of MXene by utilizing the wet ball milling process. Due to the electrostatic attraction effect, positively charged poly(diallyldimethylammonium chloride) (PDDA) long chains would attach to negatively charged MXene, which prevented the newly peeled-off MXene sheets from agglomerating and reduced the collision from the steel balls. Also, the attached PDDA molecule may act as protective shield for MXene nanosheets, leading to the delay of oxidation on the surface of MXene nanosheets in atmosphere. Notably, with the incorporation of 3 wt% PDDA modified MXene in thermoplastic polyurethane (TPU) matrix, the peak heat-release rate (decreased by 50%) and total smoke production (decreased by 47%) were significantly decreased. Moreover, mechanical performance (tensile strength at break was raised by 31.2%) and thermal conductivities (increased by 88.6%) of TPU nanocomposites were evidently enhanced. This novel strategy provide a simple and effective way to obtain exfoliated and functionalized MXenes nanosheets, enriching the application of MXenes in polymeric material field.