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

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 TiCT-stabilized HIPE templating.

EXPERIMENTS

Hydrophilic TiCT flakes are delicately hydrophobized with a double-chain cation surfactant. The morphology of TiCT flakes is investigated by transmission electron microscopy (TEM) and atom force microscopy (AFM). The surface properties of modified TiCT are characterized by zeta potential and water contact angle tests. The stability of TiCT-stabilized emulsions, and the structure of prepared ECPCs are systematically investigated.

FINDINGS

Surface modified TiCT 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 TiCT flakes. The TiCT 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 TiCT, the prepared porous polymer composites exhibit good conductivity even with ultralow TiCT content of 0.016 vol%.