Researchers and collaborators of Ningbo Institute of materials, Chinese Academy of sciences have made important progress in the study of polymerization induced monomer penetration of graphene monolayer

Graphene is a two-dimensional atomic crystal formed by the combination of single-layer planar carbon atoms in the form of SP 2 hybridization, which is expected to be an ideal material for the preparation of membranes with high permeability and high selectivity for separation and permeation Therefore, it is of great significance to study the behavior of organic molecules passing through graphene Although many theoretical predictions have been put forward in the literature, the experimental evidence of organic molecules passing through graphene in reality is quite rare because graphene without any defects is impenetrable to most atoms and molecules, which is equivalent to a high barrier "Golden Bell Jar" Theoretically, it is predicted that helium molecules will not be able to penetrate even for chemical vapor deposition (CVD) graphene with stone Wales defects In view of this, recently, Dr Zhang Tao of Professor Rainer Jordan's research group of Dresden University of technology, Germany, and researchers of Chen Tao's research group of Ningbo Institute of materials technology and engineering, Chinese Academy of Sciences and other units proposed a new idea through experiments and theoretical prediction, namely Surface initiated controlled radical polymerization can induce vinyl monomers to penetrate the monolayer graphene as a "Golden Bell Jar" In their study, initiators can be selectively bonded to the solid substrate surface to drive monomer movement and subsequent replenishment Under the condition that the initiator and the monomer are isolated by a single layer of CVD graphene, they proved that vinyl monomers of various sizes can pass through the single layer of CVD graphene under the driving of the initiator and successfully realize the surface initiated polymerization Their research found that graphene with only atomic layer thickness could not block the Coulomb force between the initiator and the monomer (as well as the catalyst), thus realizing the driving and migration of the initiator to the monomer at the other end of graphene At the same time, the properties of controlled radical polymerization make the monomer can be transported to the other end of graphene continuously at a stable rate, and the polymer molecular brush can be obtained on the surface covered by graphene Finally, by studying the thickness and morphology of polymer brush covered with graphene, we can calculate the behavior and rate of many kinds of monomers passing through graphene monolayer The final results show that various sizes of neutral monomers can successfully pass through CVD graphene with defect sites in the monolayer driven by controlled radical polymerization, and the natural defects of CVD graphene are greatly increased due to the penetration of monomers However, due to the interaction of electric charges, The monomer with positive or negative charge is seriously blocked when it passes through graphene, and the speed is quite slow Interestingly, when using micro patterned initiator arrays, anionic monomers can selectively cut graphene into a variety of preset size micro patterns when they are induced to penetrate graphene monolayers, thus obtaining patterned polymer brushes By applying external driving force to the molecules, the organic molecules such as polymerized monomers with larger molecular weight can pass through the single-layer CVD graphene, and the effect of molecular charge on the penetration behavior is greater than the size of the molecule itself These studies provide new evidence for the penetrability of graphene monolayers and new ideas for their potential applications as molecular sieves The results were published on nature communications (NAT Commun 2018, 9, 4051) The above work was supported by the State Scholarship Council, the National Natural Science Foundation of China (51573203), the key research project of Frontier Science of the Chinese Academy of Sciences (qyzdb-ssw-slh036) and the Key Laboratory of marine new materials and application technology of the Chinese Academy of Sciences.