Effects of Ion Bombardment and Humidity on Polymer Films

This study examines wrinkling behavior of Poly(4-Vinylpyridine) (4-VP), (Hydroxyethyl)methacrylate (HEMA), and 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (V4D4) polymer thin films bombarded with Ar+ ions. When held in a humid environment post bombardment, HEMA developed nanopatterning within a few hours, reaching hundreds of nanometers in height. Other samples exhibited nanopatterning as well, with V4D4 also developing holes on the surface. When held in a dry chamber instead, 4-VP and HEMA showed no signs of nanopatterning at all, while V4D4 showed slight wrinkles on its surface. To measure chemical structural changes in-situ, some of the experiments utilized an ion sputtering gun within an X-ray photoelectron spectroscopy (XPS) system. By studying bombardment results with in-situ XPS, combined with post facto characterization using atomic force microscopy (AFM), one can begin to understand the chemical and physical causes of wrinkle pattern formations.<br/><br/>This work was partly supported by NSF DMR-2117509.