Invited by the School of Chemistry and Materials Science of Nanjing Normal University and the Jiangsu Key Laboratory of Long-Duration Energy Storage Technology, Professor Zhikun Zheng of Sun Yat-sen University visited the School on July 17, 2026, for academic exchange and delivered an academic lecture entitled “Explorations in the Synthesis of Large-Area Isoporous Covalent Organic Framework Membranes” in Conference Room 224 of Huaxing Building. The event was hosted by Professor Hanjun Sun and attended by faculty members and students of the School.
Zhikun Zheng, a native of Linyi, Shandong Province, is a professor at Sun Yat-sen University and a leading talent in scientific and technological innovation under the National “Ten Thousand Talents Program.” He received his Ph.D. from the Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, in 2008, and subsequently conducted postdoctoral research in the Department of Polymer Physics at Bielefeld University, Germany. In November 2013, he became a research group leader at the Institute of Polymers, ETH Zurich, in the team of Academician A. Dieter Schlüter; in October 2014, he became a research group leader in the team of Academician Xinliang Feng at Technische Universität Dresden. In 2017, he received support from a national high-level talent program for young professionals, returned to China full time, and joined Sun Yat-sen University. His research focuses primarily on the controlled fabrication of organic porous membranes and their applications in precision separation, as well as polymer-based optical encryption materials. As corresponding author, he has published more than 70 papers in journals including Nature and Nature Chemistry, and has led projects including the National Natural Science Foundation of China International (Regional) Cooperation and Exchange Program (China–Germany) and the National Natural Science Foundation of China General Program.
In the lecture, Professor Zheng systematically presented the design concepts, synthetic methods, and related research advances concerning large-area isoporous covalent organic framework membranes. He first addressed the key scientific challenges currently facing the field of membrane separation, noting that conventional membrane materials often struggle to achieve both high-precision recognition and highly efficient mass transport when separating organic small molecules of similar size. A persistent trade-off therefore remains between separation selectivity and permeation performance. Accordingly, the construction of new membrane materials featuring uniform pore sizes, continuous through-pore channels, and large-area continuous structures has become a core issue requiring urgent resolution in the field of high-precision molecular separation. On this basis, Professor Zheng further explained why new membrane materials and new membrane synthetic chemistry are needed. He pointed out that the controlled preparation of large-area isoporous membranes with continuous through-pores involves not only the molecular structural design of the membrane materials themselves, but also precise cross-scale regulation from microscopic pore structures to macroscopic membrane morphology. However, existing synthetic methods still have evident limitations in membrane area, pore-size uniformity, pore-channel continuity, and mechanical stability. The controlled synthesis of large-area, high-quality isoporous membranes therefore remains a major challenge in the field. There is consequently an urgent need to develop a new form of large-area precision synthetic chemistry that combines molecular-scale structural precision with macroscopic membrane-forming capability. Professor Zheng then introduced the research group’s overall strategy: through multilevel precise structural control from the molecular scale, through the mesoscale, to the macroscale, the group ultimately seeks to obtain covalent organic framework membranes with large areas, continuous through-pore channels, uniform pore sizes, and good mechanical properties. To achieve this overall objective, the group divided the membrane-construction process into three interconnected steps. First, starting materials with relatively large dimensions and high structural integrity are synthesized to provide basic structural units for the subsequent formation of large-area membranes. Second, the crystallization process, interfacial reactions, and pore-channel arrangement are regulated to achieve a high degree of uniformity in the internal pore structure and pore-size distribution. Third, while maintaining uniform pore channels and efficient mass-transfer performance, the mechanical strength and structural stability of the membrane materials are further enhanced to meet the application requirements of practical separation processes. Finally, Professor Zheng provided a detailed account of the group’s specific research on isoporous covalent organic framework membranes. To address the difficulty of simultaneously achieving crystallinity and stability in covalent organic framework materials, the limited continued growth of crystal size, and the poor solubility and infusibility of these materials, which make their further processing into continuous membranes difficult, the group proposed a strategy of introducing structure-directing agents to regulate interfacial crystallization. By regulating monomer arrangement, interfacial reactions, and crystal growth, the structure-directing agents can reduce disorder during crystallization, decrease the entropy loss generated in the crystallization process, and promote the ordered nucleation and continuous growth of covalent organic frameworks at the interface. This enables direct membrane formation and avoids the difficulties encountered when conventional powder materials undergo subsequent processing. In addition, the group conducted in-depth studies of defect structures in covalent organic framework membranes, the causes of defect formation, and methods for regulating them. Given that the structures and origins of defects within membranes remain insufficiently understood, that defects are difficult to eliminate effectively, and that conventional methods for reducing the effects of defects generally require increasing the thickness of the membrane layer—thereby increasing transmembrane mass-transfer resistance—the group proposed an external-field-driven defect-repair strategy. By adjusting external conditions such as the solvent and temperature, this strategy drives multilevel dynamic covalent networks to undergo motion and reconstruction, bringing functional groups at defect sites that have not yet participated in the copolymerization reaction into closer proximity and enabling them to form covalent bonds, thereby achieving in situ repair of defects within the membrane. After this regulation, the dimensions of residual defects in the membrane can be further reduced to below the separation pore size required for the target molecules. This improves the structural integrity, separation precision, and overall stability of the membrane materials without markedly increasing membrane thickness or transmembrane mass-transfer resistance.
Professor Zheng’s lecture was rigorous in logic and highly forward-looking academically. During the question-and-answer session, Professor Zheng engaged in in-depth discussions with the faculty members and students present on the synthesis of covalent organic frameworks and related topics. The lecture concluded successfully amid warm applause from all those present.