Processing 2D nanomaterials into inorganic-polymer composite films and fibers with well-defined properties

Abstract: 2D materials such as graphene, graphene oxide (GO), reduced graphene oxide (rGO) and MXene, possess unique properties, e.g., high carrier mobilities, mechanical flexibility, good thermal conductivity, and high optical and UV adsorption. They are potentially applicable in the fields of electronics, optoelectronics, catalysts, energy storage facilities, sensors, solar cells, lithium batteries, and so on. Normally, weak interactions and irregular packing or stacking of 2D layers may adversely offset or weaken to some extent their 2D effects such as mechanical and electrical properties at a macroscale. In this regard, it is required to spatially organize 2D materials into macroscopic forms of a well-defined shape (e.g. fibers, films, or 3D structures) in a way that can simultaneously preserve favorable 2D properties and functions shown at the nanoscale, and facilitate their compatibility with the state-of-the-art industrial processes. In my thesis, different types of 2D materials, here GO, rGO and MXene together with polymers were rationally assembled into functional composite materials. The synergistic molecular crosslinking strategy was utilized and controlled in such composite materials for the sake of better performance. My thesis mainly involves four parts: (1) Tough and strong GO composite films via a polycationitrile approach. The interface between GO nanosheets was reinforced via an intermolecular covalent crosslinking approach called “polycationitrile chemistry”. As a result, the mechanical performance of the as-prepared GO-based composite films was enhanced and maintained even at an extremely high relative humidity of 98%.(2) rGO-poly(ionic liquid) (PIL) composite films with high mechanical performance. The rGO/PIL composite films were designed and fabricated, where the synergistic supramolecular interactions between PIL and rGO layer enable high electrical conductivity and favorable mechanical properties.(3) Regenerated cellulose (RC)/MXene composite nanofibers for personal heating management. I harnessed a biodegradable RC-based fibrous matrix to bond with inorganic MXene nanoflakes via electrospinning method. Via hybridization, the as-formed RC/MXene nanofibers present a promotion of mechanical performance and photothermal conversion capability. As a personal heating cloth, it realizes energy-saving outdoor thermoregulatory.(4) RC/MXene solar absorber for solar-driven interfacial water evaporation. The RC/MXene composite nanofibers integrate considerable merits of excellent mechanical performance, wettability, and fast steam generation rate. The RC/MXene solar absorber offers significant values for the practical application of solar-driven steam generation.