Production of High-Performance Membranes Using 2D Nanofibre Networks
There is an increasing demand worldwide on advanced two-dimensional (2D) nanofibrous networks with applications ranging from environmental protection and electrical devices to bioengineering. We have had a long-standing interest in the design and development of the ultrafine nanofibre materials. Herein, we report a direct electronetting technology for the production of self-assembled 2D nanofibre networks (nano-nets) from various materials.
Nature offers a simple yet efficient idea associated with ultrafine material assembly: creating a continuous fibrous network can substantially improve material utilization and the resultant properties. There are many vivid cases, such as, dragonfly wings, spider webs and honeycombs. Inspired by such biostructures, we think that, by assembling 2D continuous and ordered nanofibrous networks into a mechanically robust porous assembly, could be an effective strategy for maximizing their performance to facilitate widespread applications.
We proposed a collector inductively coupled direct electronetting technique to assemble various micro-/nanoarchitectures including microspheres, beaded fibres, beaded nanofibre nets and nano-nets. By tailoring the electrostatic field, extremely diluted precursor solutions of high-molecular weight polymers are charged, and ejected from a metal needle, forming a levitating cluster of charged droplets. Through a stretching and solvent evaporation process, these droplets deform and phase separate before they self-assemble a 2D nanofibre network based membrane.
Origin, evolution and regulation of 2D nano-nets during direct electronetting. Ejection and deformation of the charged droplets; and the trigger of assembly of different architectures using collector inductively coupled direct electronetting strategy.
Because of the simplicity and flexibility of our methodology, great versatility in controlling the material category of the resultant 2D nano-nets is possible. Until now, we have prepared not only the polymeric nano-nets of PVA, PA-6, PAN and PMIA but also the inorganic nano-nets of TiO2 and carbon obtained by combining with a calcination process. All these nano-net membranes show mechanical robustness and benefit from nanostructural properties, such as true nano-scale diameter, large specific surface area, and high porosity and extremely small pore size while maintaining a strikingly low thickness. Furthermore, some fascinating “nano-effect” is expected, including enhanced surface wettability and robust light transmittance due to their unique nanoarchitectured network structures.
We also studied the functionality of nano-net membranes for applications of air filtration, liquid separation, electric conduction and bioprotective activity. Benefitting from the synergistic effect of nanoscale fibres and well-controlled network assembly, almost all the performance are greatly improved compared to the similar existing cutting-edge materials. We can expect that such exceptional methodology for creating nano-nets will offer a versatile platform for the design and development of high-performance fibrous materials for various applications.
Read more details in our publication at: https://www.nature.com/articles/s41467-019-09444-y.