Research Projects

Novel solid-state membranes with pore sizes approaching ionic and molecular sizes are very important for desalination, fuel cells, gas separation, isotope separation, electrodialysis, dehumidifier, and many other applications. The key to success lies in our ability to create well-controlled fluidic structures on membranes. Can we utilize Alan Turing's morphogenesis theory to create new generation membranes? Turing patterns are theoretically predicted to form by the pairing of reaction and diffusion processes. A recent study published in ‘Science’ (Tan, Zhe et al. 360, 518 (2018)) suggests that by controlling the polymeric reaction of activator and inhibitor, one can achieve Turing patterns with better desalination properties. On the other hand, 2D (two-dimensional) materials excited the membrane community due to their ability to form layered structures with tunable interlayer spaces and showed excellent filtration properties. However, membranes with 2D materials lack on many fronts such as mechanical instability, swelling in water, and also defects and pinholes in the membrane degrade its long-term performance. In contrast, polymers are known to possess great mechanical integrity, flexibility and ease of fabrication. The proposal aims to combine good properties of both polymer and 2D materials/or Metal Organic Frameworks (MOF) to create well-defined pores/channels in membranes. For example, seawater purification requires membranes that have pores/channels smaller than the hydrated size of the salt ions, which is ~6-8 Å. Gas separation demands a much smaller pore size window of 2-4 Å, related to the kinetic diameter of gasses. Our aim is to obtain different kinds of Turing patterns and try to understand their effect on filtration properties such as desalination and gas separation. Fabricating membranes with small pore sizes is not at all an easy task. This requires optimization of the concentration of 2D materials and their nature, their coverage, diffusion coefficients of activator and inhibitor, reaction time, etc. For 2D materials, we would choose vermiculite, graphene oxide, and MXenes. These materials are chosen so that they can be suitably modified to change the surface properties. The success of the project would lead to the integration of polymers with a variety of multifunctional materials like zeolites, metal-organic frameworks, etc. There are attempts to combine polymers with 2D materials, MOF, etc. but our strategy is to obtain Turing strip patterns, which is a confined geometry and hence expected to show outstanding permeation properties. Moreover, vertically aligned flow membranes with uniform thickness are very rare and, in this project, we aim to synthesize vertically aligned Turing fluidic structures. With this study, a better understanding of the transport mechanism through low-dimensional fluidic channels is envisaged.