Hyper-Thin Membrane Project
The need for improved methods of separating gases is becoming increasingly apparent. One important example is the separation H2 from CO2. Specifically, current efforts that are being aimed at moving the United States towards a hydrogen fuel economy face many major challenges, one of which is the development of more energy-efficient methods for purifying H2, which is generated from reforming processes.
This program focuses on the creation of new classes of hyper-thin (<100 nm) membranes that may lead to highly-energy efficient methods of separating H2 from CO2, and other gas mixtures that are of industrial importance; e.g., H2/N2, O2/N2, etc. Specifically, this research involves the synthesis and characterization of single, porous and "glued" (i.e., ionically cross-linked) Langmuir-Blodgett (LB) bilayers that are expected to show permeation characteristics that place them above the "upper bound" for He/CO2, due to the intervention of molecular sieving, This upper bound represents a theoretical line that defines the maximum He/CO2 permeation selectivity and maximum He permeability that is expected for solution-diffusion mechanisms of transport. Although these studies lie at the basic science level, recent advances in continuous LB film deposition should allow for the large-scale synthesis and manufacturing of such membranes. In a broader context, this research will significantly expand the chemistry of glued LB bilayers, which should encourage other researchers to revisit the possibility of exploiting the nonlinear optical, piezoelectric, pyroelectric, semi-conducting, sensing and barrier properties of LB films from a practical standpoint.
Experimental techniques that are utilized in this project include organic synthesis, polymer chemistry, Langmuir-Blodgett film formation, and a variety of analytical methods for film characterization; e.g., gas permeation, ellipsometry, X-ray photoelectron spectroscopy, contact angle and surface viscosity measurements.