ABSTRACT
The development of gas separation membranes dates back to the early nineteenth century. It has got momentum after the discovery of high-ux asymmetric membranes by Loeb and Sourirajan in 1964. Mixed matrix membrane (MMM), comprising rigid permeable or impermeable particles, such as zeolites, carbon molecular sieves (CMSs), silica, titania, and carbon nanotubes (CNTs), dispersed in a continuous polymeric matrix presents an interesting approach for improving the separation properties of polymeric membranes. The particles are referred to as nanollers if they are in nano dimensions, and correspondingly the MMMs are referred to as nanocomposite membranes. In this approach, using properties of both the organic and inorganic phases, a membrane with good permeability, selectivity, mechanical strength, and thermal as well as chemical stability and processing can be prepared. Superior gas separation properties of molecular sieve materials can be combined with desirable mechanical properties and convenient processing of polymers. Inorganic materials that are used as the dispersed phase in MMMs have unique structure, surface chemistry, and mechanical strength. When they are added to the polymer matrix, it is expected that the resulting membrane properties become better than those conventional polymer membranes. Very few studies have been carried out to increase the performance of gas separation membranes with MMMs.1-4 Preparation of MMMs usually involves difculties such as weak contact of particles in the polymer matrix and poor distribution of the dispersed phase in the continuous polymer matrix phase. In addition, particle size, particle pore size, dispersed phase load, and polymer type and properties can affect the mixed matrix properties. Preparation of defect-free membranes with desired performance characteristics is quite challenging.
