Preparation and characterization of ultrathin, gas selective membranes based on layer-by-layer self-assembly technique

• Main Author: Aw, Rachel Rui Shi
• Other Authors: Lua Aik Chong
• Format: Final Year Project
• Language: English
• Published: 2012
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/49632
• Institution: Nanyang Technological University

Membranes are good porous materials used for the segmentation of adjacent materials, regulating the transport of materials across the membrane by acting as a barrier. A good membrane needs to have good mechanical and thermal properties, as well as good gas separation properties which are permeability and selectivity. However, there is a trade-off between permeability and selectivity. Thus, the project was initiated to deduce the best combination of the parameters of a membrane, to strike a balance between the two gas separation properties. Composite membranes were chosen because such membranes possess advantages of both organic and inorganic membranes. Layer - by -layer self assembly method was carried out as it was able to obtain membranes with ultrathin and well-controlled thickness in nanometre scale. The variables of the membranes that were analyzed in this project included, the size of the pore of the porous alumina substrate, the number of bi-layers of the polyelectrolyte solution coated, the type of anion polyelectrolyte solution used and the concentration of the anion solution. Membranes prepared were tested with pure gases oxygen, carbon dioxide, nitrogen and helium and effect of the size of gas molecules on the permeability and selectivity was analyzed. Membranes were tested using a gas transport setup and the surface morphology was further analyzed using Scanning Electron Microscope (SEM).