MXene and cellulose nanocrystal co-stabilized Pickering emulsions and their applications as templates to fabricate photothermal phase change material microcapsules

Abstract

Pickering emulsion (PE) is a versatile approach to constructing oil–water interfaces, microcapsules, and nanocomposites. The poor Pickering emulsifying ability of MXene limits its wide application. Many approaches have been developed to enhance the Pickering emulsifying ability of MXene by chemical surface modification. However, surface modified MXene generally suffers from unsatisfactory emulsifying ability and severe property deterioration. Herein, we employed a cellulose nanocrystal (CNC) as a Pickering co-stabilizer to facilitate the assembly of MXene at an oil–water interface and enhance the Pickering emulsifying ability of MXene, leading to MXene/CNC (MC) co-stabilized PE. The emulsion size decreased with CNC and MXene concentrations, and the continuous water phase was transparent after creaming, indicating that CNC and MXene were both fixed at the oil–water interface as emulsifiers. CNC and MXene were assembled by hydrogen bonds and stabilized PE via partial wettability with both oil and water phases instead of reducing interfacial tension. The application of MC co-stabilized PE was demonstrated by employing it as a template to fabricate photothermal phase change material (PCM) microcapsules. The obtained PCM microcapsules with MC as a shell exhibited high phase change enthalpy, leak-proof stability, and photothermal conversion ability. Therefore, PCM microcapsules containing MXene are promising for solar energy harvesting and thermal management applications. This study provided a powerful tool to construct MXene based advanced functional materials via MC co-stabilized PE.