Abstract:

Significance Nanofiber membrane made by electrostatic spinning has the advantages of small fiber diameter, rich pores in the membrane, small porosity, large specific fiber surface area, and easy functional modification. In recent years, nanofiber membrane has shown broad application prospects in the fields of water treatment, new energy, biomedicine and so on. The molecular structure of metal-organic framework (MOF) has the advantages of high specific surface area, uniform pore size and adjustable structure. It is difficult to give full plays to its performance advantages in the fields of flexible functional film and large-area device. Therefore, it is necessary to make full use of the material properties of electrostatic spinning nanofibers with intrinsic flexibility and easy to achieve large-area preparation. The research and development of polymer composite metal-organic frame functional nanofiber membrane materials based on electrostatic spinning is of great significance to broaden the application field of MOF materials.
Progress In this paper, the feasibility of combining metal-organic skeleton with electrospinning membrane is introduced, and the preparation, development and latest research progress of polymer composite metal-organic skeleton functional nanofiber membrane are reviewed. In addition, the applications of electrospun polymer composite metal-organic skeleton functional nanofiber membranes in water treatment, lithium battery separator, drug delivery, gas separation and other fields are systematically classified and discussed. At present, there are many reports on the research of MOF and polymer blending silk, and the preparation methods can be summarized into three types, i.e. (i) polymer solution spinning mixed with MOF particle, (ii) polymer nanofiber membrane modification with MOF and (iii) one-step blending spinning method. For the first methord, MOF particle mixed polymer solution spinning firstly synthesized MOF powder by traditional method, then dried MOF powder was mixed into the spinning solution by ultrasonic dispersion or high temperature dissolution method to prepare polymer mixed metal organic frame powder functional nanofiber membrane. In the second method, the polymer nanofiber membrane was modified by MOF. In this process, ordinary nanofiber membrane was prepared by traditional method, and then the prepared nanofiber membrane was placed in MOF stock solution, and MOF particles were grown on the surface of the nanofiber membrane. In the one-step blending spinning method, MOF and spinning stock are mixed in a specific ratio before electrospinning. The formation of MOF powder occurs simultaneously with the formation of fiber. One-step blending not only simplifies the preparation process, but also disperses MOF uniformly on the polymer fiber. By simplifying the synthesis of conventional MOF composite nanofibers into one step, it has better applicability to more polymers. At the same time, the problems of phase separation between MOF and polymer and aggregation of MOF in the preparation process are avoided, causing change in material properties. The electrospun polymer composite metal-organic frame functional nanofiber membrane has better characteristics than the pure polymer membrane, such as higher porosity and higher specific surface area, and has application potential in medical treatment, new energy and environmental treatment, which is of great significance for the realization of environmental sustainable development.
Conclusion and Prospect The development potential and existing problems of polymer composite metal-organic framework functional nanofiber membranes in recent years were summarized, and the future development trend of this research field was prospected. Although advances have been made in many areas of electrospun polymer/MOF functional nanofiber membranes, some challenges remain. ① The compatibility between MOF and polymer should be considered in the synthesis process. ② The high temperatures required for most functional nanofiber synthesis processes limit the use of heat-sensitive fibers. ③ During the use of functional nanofibers, the degradation of MOF may hinder its function. ④ Durability and functional regeneration. ⑤ We need to consider the actual situation. For example, some functional nanofiber membranes can only work under certain conditions, such as photoinduced antibacterial MOF/fibers requiring sunlight. Therefore, functional nanofibers with more functions are more likely to become a viable technology. In order for electrospun polymer/MOF functional nanofibers to be widely used, it is necessary to develop low-cost, sustainable synthesis methods and further study the key properties of functional nanofibers such as mass load, BET, coverage and uniformity. The open grid structure of MOF material makes it easy to be chemically modified and can conform to reasonable expectations.

Key words: electrospinning, metal-organic framework, functional nanofiber, water treatment membrane material, lithium battery separator material, drug delivery, gas separation