Laetitia Bernard oral presentation (OB2-Mon2-2-3)
The versatility of ToF-SIMS for the study of functional plasma polymer film gradients
1 Empa, Lab for Nanoscale Materials Science, Überlandstrasse 129, 8600 Dübendorf, Switzerland
2 Empa, Lab for Advanced Fibers, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland
3 Empa, Lab for Biointerfaces, Lerchenfeldstrasse 5, 9014 St. Gallen, Switzerland
Controlling the balance between functionality and stability in grown plasma polymer films (PPFs) is the key to diverse applications such as drug release, tissue-engineered implants, filtration, contact lenses, microfluidics, electrodes or sensors. Highly func-tional plasma polymer films typically show a limited stability in air or aqueous envi-ronments due to molecular reorganization, oxidation and hydrolysis. Stabilization is achieved by enhancing crosslinking at the cost of the terminal functional groups such as −OH, −COOH, or −NH2. To overcome this, vertical structural and/or chemical gradients composed of a highly crosslinked base layer gradually changing into a functional surface termination can be fabricated. Also, patterned lateral gradients can allow the tuning of surface functionalities, and can for example provide valuable test bench for the im-mobilization of proteins. Besides techniques that probe the various (macroscopic) func-tionalities and stability of these films, several studies report correlated chemistry, mainly based on XPS elemental characterization of the grown films and subsequent interpretation of the processes involved at the molecular level.
Here we use ToF-SIMS to gain direct and local molecular information for different ver-tical and lateral plasma polymer film gradients. We show how ToF-SIMS, within its various operation modes, can be used to assess very subtle chemical and crosslinking changes upon film deposition parameters, that reveal to strongly influence the final sur-face functionality and/or stability.