Research Training Group 2154 - Materials for Brain

P4: Controlled drug release via stimuli sensitive barrier coatings deposited by initiated chemical vapor deposition (F. Faupel)

Initiated chemical vapor deposition (iCVD) permits gas phase deposition of many polymers with structure and properties very similar to their well-known wet chemically synthesized counterparts. This also includes stimuli sensitive polymers. In P4, iCVD is used to deposit tailored polymer coatings for controlled drug release. One aspect, explored together with project P3, is applying concepts borrowed from microelectronics to release drugs with both, temporal and spatial control. The deposited polymer layers are characterized using different analytical tools, like FTIR, Raman spectroscopy, AFM and XPS to name a few. Moreover, release measurements are performed.

In the present PhD thesis, emphasis is put on stimuli sensitive barriers reacting on internal or external stimuli such as temperature or AC magnetic fields, respectively. These are inter alia of interest for P5. Temperature sensitivity result from a tailored glass transition temperature Tg, which marks the transition from the glassy state blocking permeation to the rubbery highly permeable state. Tg can be tailored, e.g. by insertion of flexible spacers or bulky side groups into the polymer or the degree of crosslinking. Incorporation of magnetic nanoparticles, co-deposited form a gas aggregation cluster source, allows switching of the barrier properties via an external AC magnetic field. In this approach, the polymer barrier is heated above the glass transition temperature by the magnetic nanoparticles.  Gradual control of the barrier properties without switching can also be achieved in an approach not resorting to the glass transition.