| AVS 54th International Symposium | |
| Surface Science | Thursday Sessions |
| Session SS-ThP |
| Session: | Surface Science Poster Session |
| Presenter: | L. Yang, Brigham Young University |
| Authors: | L. Yang, Brigham Young University F. Zhang, Brigham Young University N. Shirahata, National Institute for Materials Science, Japan T. Nakanishi, National Institute for Materials Science, Japan M.R. Linford, Brigham Young University |
| Correspondent: | Click to Email |
Here we describe a method for probing the surface free energies of materials by stamping them with polydimethylsiloxane (PDMS) stamps that have also been wet with low molecular weight PDMS. Hydrophobic surfaces, e.g., alkyl monolayers with high advancing water contact angles, resist adsorption of PDMS, while PDMS adsorbs effectively onto hydrophilic or even moderately hydrophobic surfaces. For example, PDMS transfers to thin films of C60, while it does not transfer to thin films of molecules that contain long alkyl chains. In addition, PDMS transfers to hydrophilic spots patterned onto hydrophobic monolayers, but not onto the background. The degree of PDMS transfer can be used to monitor processes such as the contamination of a clean metal surface in the ambient. The PDMS transferred in these cases is easily detected by spectroscopic and imaging time-of-flight secondary ion mass spectrometry (ToF-SIMS) because of the sensitivity of this technique for this species. Wetting, X-ray photoelectron spectroscopy, and principal components analysis of the ToF-SIMS data are also employed to study this problem.