UV-Ozone Contact Angle Measurements
Last week I made a post showing the diffusion of DDM and BSA through SC267. I an effort to increase the negative charge associated with the membrane material I proposed using UV-Ozone exposure.
A while back there was some concern that the UV-Ozone system was contaminated by PDMS, and that a standard cleaning protocol needed to be used to remove the contaminants. Tom had proposed running the system for 15min with vaccuum at 150C to “clean” out the PDMS. After this was proposed we never took the time to investigate if this proceedure really worked.
Justin and I have begun working to characterize the contact angles resultant from different length UV-Ozone exposures, after Tom’s cleaning protocol has been performed. At the end of last week using Si-shards we ran multiple samples through the UV-Ozone system for different length of time (0, 2, 5, 10, 15, and 20min) at 150C. The plot below shows the relationship between UV-Ozone exposure and measured contact angle. The blue points represent the contact angles measure immediately after UV-Ozone treatment and the red points represent contact angles measured on the same samples only 24-hours after initial treatment.
Unfortunately, the oxygen tank ran out on Friday and as a result we are going to repeat these trials to ensure accuracy. While the treatment seems to improve the hydrophillicity of the membranes surface we are not yet sure if this is a result of the “deposition” of a hydrophillic polymer such as PDMS on the samples surface. To test for this we plan on running samples through the UV-Ozone system and then conducting simple diffusion experiments with positive (Rhodamine 6G) and negative (Fluorescein) dyes.