Crosslinked Membranes with Non-Collapsible, Uniform Pores of Sub-nanometer Size

1066947 Gong Organic nanotubes with non-deformable pores of precisely controlled diameters are rare. This research aims to create robust assembly of rigid nanotubes with modifiable surfaces, and a nondeformable, sub-nanometer pores, based on chemical synthesis, self-assembly, fabrication of nanoporous membranes, and computational modeling and optimization. The nanotubes to be created are cylindrical stacks of donut-like molecules. The great potential of the proposed method lies in its ability to control or tune the size and function of a sub-nanometer pore or nanopore. It is becoming increasingly clear that channels of reduced diameters, particularly those in the sub-nm range, may completely reject metal ions while still allowing water to pass through. The proposed method also allows additional chemistry to be introduced into the subnanometer pores, which are expected to demonstrate very efficient water transport and remarkably high ion selectivities and could therefore overcome the last major hurdle in developing artificial membranes capable of rivaling their natural counterparts. These selfassembling pores may be fine tuned to repel salt, ions, or water features that are unprecedented for currently known synthetic pores. The availability of these structurally simple, synthetically readily available nanopores with tunable, perfectly monodisperse diameters should open a new avenue to the fabrication of highly efficient, practical membranes for applications ranging from water purification to separations of various molecules. The intellectual merit of the proposed research lies in the integration of concepts from multiple scientific fields including organic, inorganic, supramolecular, physical, and polymer chemistry for nanoporous membrane fabrication. Besides the tremendous potentials provided by the proposed strategies for fabricating membranes with nanopores of a uniform size, this project represents a new, realistic approach for constructing membranes having sub-nanometer pores, which should address one of the major challenges in membrane science. Developing the nanoscale molecular and supramolecular chemistry, along with the corresponding nanotubular assemblies and their further engineering should make fundamental contribution to the understanding of molecular and supramolecular interactions on the nanometer scale, insights from which should greatly facilitate the development of novel nanostructures of the next generation. The broader impact of this research involves its highly interdisciplinary nature, based on which students of various backgrounds will gain skills in multiple fields including chemistry, materials science and the engineering of the corresponding molecules and devices. Specifically, the educational impacts of this research include: (1) The opportunity to combine computer-aided design, synthesis, and characterization of molecular, supramolecular, and nanosized structures with the engineering of the resultant materials and devices in training graduate students; (2) the proposed research encompasses a broad range of background and skills and will thus be especially suitable for the participation of undergraduate students. Aggressive efforts have been successfully, and will be continuously, made by the PI to recruit undergraduate students from groups of traditionally underrepresented groups in sciences, from multiple channels. These include the NSF-REU program, the Collegiate Science and Technology Entry Program (CSTEP) at SUNU Buffalo, established collaborations with undergraduate institutions in the area, and the sophomore-level organic chemistry course the PI has been teaching in recent years; (3) the research results will be published in highly visible journals to broadly disseminate this work to scientific society at large, and will lead to many practical applications. Insights obtained from the environmentally significant and urgent problem of water purification and desalination, which is the focus of this application, will help the development of concepts that are generally useful for addressing other problems in the field of chemical and biological separation.