Research Training Group 2154 - Materials for Brain

Maximilian Burk

mabu@tf.uni-kiel.de

iCVD of photoresponsive polymer thin films

Initiated chemical vapor deposition (iCVD) can best be described as radical polymerization directly from the gas phase in a low pressure environment. The resulting polymer thin films are synthesized directly onto the cooled substrate while maintaining the specific topography of the surface as well as chemical functionality of the used precursors. This makes iCVD an ideal technology for coating of sensitive materials such as membranes, foils or even medical components since no solvents are involved in the process.
In my work, I was first to show co-polymerization of a novel type of chromophore via iCVD, enabling the equipment of almost every kind of substrate with photochromic properties. Chromophores such as azobenzenes, diazocines or spiropyrans possess the ability to switch between two stable states upon irradiation with a specific wavelength. This is of great interest for materials science, since the process of photoswitching can lead to a change of molecular size, dipole moment or absorption, representing properties which are desirable to be exploited on various kinds of functional substrates. Since no solvents are needed for the polymerization, I am able to combine highly hydrophobic chromophores with hydrophilic compounds such as hydrogels without the risk of phase separation. For investigation of my films, I use characterization methods such as XPS and FT-IR that allow a detailed insight into the chemical composition of the films, as well as ellipsometry which can be used to see photochromic properties of the incorporated chromophore in-situ.
In context of the RTG 2154 "Materials for Brain", I plan to develop novel biocompatible polymer thin films for utilization in controlled drug-release related applications. I am focused on hydrogel based photochromic thin films which can be used for enzyme-triggered release as well as biodegradable polymer coatings, in which covalent bonds are cleaved due to specific pH levels in aqueous media.

 

Max Burk