Electrically conductive porous MXene-polymer composites with ultralow percolation threshold via Pickering high internal phase emulsion templating strategy

Abstract

Hypothesis: Constructing a segregated network in electrically conductive polymer composites (ECPCs) is an effective method to lower the electrical percolation threshold. The segregated network structure can be formed naturally via polymerizing Pickering high internal phase emulsions (HIPEs) because solid particles are assembled at water-oil interfaces. However, most Pickering stabilizers show poor electrical conductivity. In this work, we propose a facile method to prepare lightweight ECPCs with well-controlled segregated structure via Ti3C2Tx-stabilized HIPE templating.Experiments: Hydrophilic Ti3C2Tx flakes are delicately hydrophobized with a double-chain cation surfactant. The morphology of Ti3C2Tx flakes is investigated by transmission electron microscopy (TEM) and atom force microscopy (AFM). The surface properties of modified Ti3C2Tx are characterized by zeta potential and water contact angle tests. The stability of Ti3C2Tx-stabilized emulsions, and the structure of prepared ECPCs are systematically investigated.Findings: Surface modified Ti3C2Tx flakes are used to stabilize water-in-oil (w/o) HIPEs for the first time. After the polymerization of continuous oil phase, ECPCs are successfully prepared with closed-cell porous structure. The pore size and size distribution of porous composites can be tailored by varying the content of Ti3C2Tx flakes. The Ti3C2Tx flakes are mainly immobilized at the water–oil interface and eventually form the segregated network in composites. Combining the unique segregated network and the outstanding metallic conductivity of Ti3C2Tx, the prepared porous polymer composites exhibit good conductivity even with ultralow Ti3C2Tx content of 0.016 vol%.