Gas separation membrane technology has great application prospects in the field of industrial separation because of its high efficiency, low energy, and environmental friendliness. The gas permeability coefficient of traditional gas separation membrane materials is very low, and it has become increasingly unable to meet the growing industrial demand. The development of high-transmittance, highly-selective membrane materials is a goal that people have been pursuing. Self-microporous polymers (PIMs) are a class of high molecular materials with high permeability and reasonable selectivity that have been developed in recent years. Their high gas permeability is derived from the inefficient folding of rigid twisted molecular chains. The inherent microporous structure. The design and development of new high-performance PIMs have significant and far-reaching significance for the development of gas separation membranes.
Recently, Wei Jian's research group at the Suzhou Institute of Nanotechnology and Nanobionics, Chinese Academy of Sciences, has built new PIMs by introducing into the polymer chain a more rigid structure with a V-shaped Stereo-Terbium (TB) structure. The PIMs construction unit SBI, Telegine base units have stronger rigidity and more suitable spatial dihedral angle, which is beneficial to enhance the microporous structure of the polymer and improve the screening effect of the polymer on the gas; further, through reasonable The interface design is a complex modification of the TB functionalized PIMs obtained, and a series of research advances have been made in the field of gas separation membranes:
By the copolymerization method, a rigid and twisted Telegram base group was introduced into the PIM-1 main chain, and a Telegram base PIM self-microporous copolymer (TBPIM) was designed and synthesized. The introduction of the Teleg base group enhances the rigidity of the polymer segment on the one hand, and on the other hand, the nitrogen atom contained in the Teleg group greatly enhances the affinity of the polymer for the CO2 molecule. The synergistic effect of the two aspects makes the TBPIM copolymer have a significant increase in the selectivity of CO2/N2, CO2/CH4, O2/N2 gas separation. The research results were published on Poly. Chem. 2014, 5, 2793-2800.
Further, in order to solve the problem of low gas permeability of the traditional polyimide material, a single rigid segment containing a Tetraganine structure was designed and synthesized from a microporous polyimide ( FIG. 1 ). The specific surface area of â€‹â€‹the micro-porous polyimide from the Teleg base is up to 300 m2/g, which is two orders of magnitude higher than that of the traditional polyimide, and the gas separation performance is improved significantly. It is close to 2008 representing the best performance of polymer gas separation. Year Robeson cap. The research results were published in ACS Macro Letters, 2014, 3, 597-601. On this basis, the anhydride and diamine parts were replaced by rigid units to obtain a self-porous microporous polyimide with double rigid segments (Figure 1). The specific surface area of â€‹â€‹the material was increased to 600 m2/g, and the gas separation performance exceeded the 2008 Robeson ceiling (Figure 2). The research was published in Macromolecules, 2014, 47, 7477-7483.
Based on this, the research group designed and prepared a polymer/metal-organic framework (MOF) mixed matrix membrane by using Trog bases with microporous polyimide as the subject material. The use of MOF ultra-high porosity and regular pore structure to achieve effective screening of gases. In order to solve the dispersion of the MOF particles in the polymer and compatibility issues with the polymer matrix, the MOF particles were surface-modified and modified to form hydrogen bonds and Van der Waals forces with the polymer body, enhancing the interfacial interactions. Improves interface compatibility (Figure 3). This kind of mixed matrix membrane material has very excellent comprehensive gas separation performance, far exceeding the Robeson ceiling (Figure 3). In addition, the composite film exhibits excellent anti-aging properties and thermal stability. The research results were published on Adv. Mater. DOI: 10.1002/adma.201504982.
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