Hydrogels produced with Initiated Chemical Vapour Deposition
K. Unger
Institute of Solid State Physics, Graz University of Technology
15:00 - 17:00 Monday 28 September 2015 Foyer Alte Technik A hydrogel is an unsolvable polymer network with hydrophilic groups. Properties like the swelling or the elastic modulus can be tuned by embedding additional functional groups during the manufacturing process. Synthesizing hydrogels with solution-based methods is often problematic due to swelling of the solvent in the hydrogel matrices.
A novel and suitable solvent-free technique is initiated Chemical Vapour Deposition (iCVD). This surface polymerization technique was mainly developed in Prof. Karen K. Gleason’s group at MIT, Boston. The initiator and monomer species enter the iCVD chamber as vapours. The initiator gets decomposed by interacting with a relatively hot filament (150 °C – 300 °C). These temperatures are enough to selectively break only labile bonds present in the initiator structure, (e.g. the O-O bond in the tert-butyl peroxide). The monomer decomposition temperatures are > 500°C, therefore the monomer fully retains its chemical structure. The mechanical properties can be irreversibly tuned by changing the degree of cross-linking of the polymer. The degree of cross-linking can be tuned with process parameters as the filament temperature, substrate temperature but especially with the chemical composition.
In this study hydrogel films with 2-hydroxyethyl methacrylate (HEMA) and ethylene glycol dimethacrylate (EGDMA) will be presented. HEMA has a temperature dependent polarisation and is hydrophilic at room temperature. EGDMA is used as a cross-linking agent for the stabilisation of the polymer network. The materials are all bio-compatible and offer a great variety of applications as sensors, in pharmaceutics or for cell cultivations.
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Institute of Solid State Physics
