Thermoplastic polyurethane - Ti3C2(Tx) MXene nanocomposite: The influence of functional groups upon the matrix-reinforcement interaction

The recently discovered MXenes are promising candidates as reinforcements for nanocomposites due to their high mechanical properties, thermal and electrical conductivities. These properties are strongly affected by the presence of surface functional groups (-O, -F or -OH), which are related to the synthesis route employed. However, there is a lack of scientific investigations concerning the influence of such functional groups on the MXene/polymer matrix interaction. Therefore, we performed density functional theory calculations to simulate the interaction between Ti3C2 MXenes with different functional groups and thermoplastic polyurethane (TPU) based molecules. It was found that the main interaction mechanisms involved were the formation of hydrogen bonds and pi-pi stacking (in the aromatic ring). Moreover, while fluorine and hydroxyl terminations favored the interaction with TPU, oxygen-terminated MXene has hindered it in three of the four configurations tested. These findings indicate the relevance of controlling the MXenes surface chemistry for improving MXenes/polymer matrixes interactions in nanocomposites.