| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2016) | |
| Biomaterial Surfaces & Interfaces | Thursday Sessions |
| Session BI-ThM |
| Session: | Plasma for Biomedical Applications |
| Presenter: | Solmaz Saboohi, University of South Australia, Australia |
| Authors: | S. Saboohi, University of South Australia, Australia B.R. Coad, University of South Australia, Australia A. Michelmore, University of South Australia, Australia R.D. Short, University of Lancaster, UK H.J. Griesser, University of South Australia, Australia |
| Correspondent: | Click to Email |
There is a growing need for thin films which are functionalized with specific surface chemical motifs that impart new physical, chemical or biological properties. The design and fabrication of thin films with specific surface groups has the potential to provide further insights into bio-interfacial interactions as well as to yield novel coatings for products such as cell culture ware. Plasma polymerization (PP) provides a one-step, solvent-free process, irrespective of material type and format, and supports several large-scale industrial applications on the basis of advantages such as excellent uniformity and adhesion of coatings and their reproducibility. We have studied how volatile ester compounds can be plasma polymerized with retention of a high density of intact structural elements. However, in PP there usually occurs extensive fragmentation of the volatile precursor molecule ("monomer") and re-assembly of the various fragments from the plasma gas phase into a solid polymeric coating. Considerable scrambling of molecular structural elements is evident even where functional group retention has been the objective. High energy electron impact events in the plasma results in loss of specific functional groups in the plasma phase. In addition, a strong negative electric field, which develops in the vicinity of the surface, may cause positive ions to arrive at the surface with significant energy. Sputtering / reorganization at the surface due to ion impingement also results in loss of specific functional groups. Retention of chemical functional groups can be optimized by considering the pressure where the plasma transitions from the alpha to the gamma regime.[1] Operating the plasma in the collisional regime biases the deposition towards increased contributions by ions rather than neutral/radical grafting.[2] This study demonstrates that relatively complex structural motifs in precursor molecules can be retained in plasma polymerization if the chemical and physical processes occurring in the plasma phase are controlled by tuning the plasma to deliver a high flux of polyatomic ions and suitable energy of the ions to deposit films.
References
[1] Liebermann, M. A. and Lichtenberg, A. J. Principles of Plasma Discharges and Materials Processing, 2nd ed. (A John Wiley and Sons, New York), 2005.
[2] Saboohi, S.; Coad, B.R.; Michelmore, A.; Short, R.D.; Griesser, H.J. Hyperthermal Intact Molecular Ions Play Key Role in Retention of ATRP Surface Initiation Capability of Plasma Polymer Films from Ethyl α‑Bromoisobutyrate, ACS Appl.Mater.Interfaces, 2016, 8, 16493−16502