Solute Permeation Through Polymeric Thin Films

The transport of small molecules through polymeric thin films is critical to a large number of applications. For example, it plays a key role in efficiency and efficacy of membranes designed for gas separations and desalination. Our interest in this area focuses on two specific applications: osmotically driven membrane processes (ODMPs) and edible protective coatings. ODMPs are a class of water treatment and energy generation technologies that have garnered attention due to their ability to produce useable water from highly impaired water sources and high salinity brines.

In ODMPs, two solutions of differing concentrations are placed on opposite sides of a semipermeable membrane, which induces the permeation of water from the less concentrated feed solution to the more highly concentrated draw solution (i.e., osmosis). Unfortunately, membranes are not perfect barriers and solutes also permeate across the membrane. Due to the unique operating geometry of ODMPs, as solutes from the draw solution move past solutes from the feed solution within the polymeric membrane, they may interact with each other, and alter their permeation rates. We are investigating how these interactions arise and affect permeation rates as well as the influence that these interactions have on the systems level design of ODMPs.

Polymer films are frequently used to protect produce from external hazards and physical damage during shipping. The biodegradability of edible polymer films provides several advantages over conventional polymer films. However, these edible films need to perform as well as existing technologies if they are going to be adapted. We are interested in understanding if edible coatings can be as effective as nonedible coatings in regulating the permeation of oxygen and carbon dioxide to and from produce.