Browsing by Subject "PDMS"

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  • Hemmila, Samu; Ruponen, Marika; Toropainen, Elisa; Tengvall-Unadike, Unni; Urtti, Arto; Kallio, Pasi (2020)
    This paper presents a novel microflow-based concept for studying the permeability of in vitro cell models or ex vivo tissues. Using the proposed concept, we demonstrate how to maintain physiologically relevant test conditions and produce highly reproducible permeability values for a range (31) of drug compounds. The apparent permeability coefficients (P-app) showed excellent correlation (0.89) with the values from experiments performed with a conventional Ussing chamber. Additionally, the microflow-based concept produces notably more concentrated samples than the conventional Ussing chamber-based approach, despite the fact that more than 10 times smaller quantities of test compounds and biological membranes are needed in the microflow-based concept.
  • Lintala, Aino-Maija (Helsingin yliopisto, 2020)
    Polysiloxanes are silicon-based polymers consisting of R2SiO repeating units. They are commonly used in many commercial applications, for example, as adhesives, additives, or waterproof coatings. This thesis concentrates on polysiloxanes used as optically clear adhesives, which are needed in display applications to, for instance, bond cover lenses to touch panel sensors. This kind of a material needs to have a high refractive index to match glass or plastic, and it has to be transparent and thermally stable. In addition, it must resist degradation and yellowing from UV exposure and humidity. Anionic ring-opening polymerization was used to synthesize optically transparent polysiloxanes with varying side-groups. These polymers exhibited high refractive index values, which were adjusted by changing the amount of phenyl group -containing monomers or with chain terminating agents. End-functionalization reactions were performed for the synthesized polymers to introduce methacrylate groups to the chain ends, which could later be used in crosslinking trials involving a photoinitiator. The results present an effective synthetic route for the ring-opening polymerization for transparent, high refractive index poly(dimethylsiloxane-co-diphenylsiloxane) and poly(methylphenylsiloxane) that could be used as adhesives after selective chain end functionalization and crosslinking reactions. The properties of the synthesized polysiloxanes were characterized with several different methods, such as size exclusion chromatography, rheology, and NMR spectroscopy. End functionalization reactions were performed for some of the synthesized polymers. These were then further characterized to verify the suitability of the reaction.