Browsing by Subject "BLENDS"

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  • Viidik, Laura; Seera, Dagmar; Antikainen, Osmo; Kogermann, Karin; Heinämäki, Jyrki; Laidmäe, Ivo (2019)
    Printing technologies combined with a computer-aided design (CAD) have found an increasing number of uses in pharmaceutical applications. In extrusion-based printing, the material is forced through a nozzle to form a three-dimensional (3D) structure pre-designed by CAD. The aim of this study was to evaluate the 3D-printability of biocompatible aqueous poly(ethylene oxide) (PEO) gels and to investigate the effects of three formulation parameters on the 3D printing process. The impact of PEO concentration (gel viscosity), printing head speed and printing plate temperature was investigated at three different levels using a full factorial experimental design. The aqueous PEO gels were printed with a bench-top extrusion-based 3D printing system at an ambient room temperature. The viscosity measurements confirmed that the aqueous PEO gels follow a shear-thinning behaviour suitable for extrusion-based printing. Heating the printing plate allowed the gel to dry faster resulting in more precise printing outcome. With the non-heated plate, the gel formed a dumbbell-shaped grid instead of straight lines. Higher concentration and more viscous PEO gels formed the best structured 3D-printed lattices. In conclusion, the accuracy and precision of extrusion-based 3D printing of aqueous PEO gels is highly dependent on the formulation (PEO concentration) and printing parameters (printing head speed, plate temperature). By optimizing these critical process parameters, PEO may be suitable for printing novel drug delivery systems.
  • Salomäki, Mikko; Jaakkola, Oskari; Hirvonen, Sami-Pekka; Tenhu, Heikki; Kvarnström, Carita (2018)
    Thin films of water dispersible poly(ethylene oxide) (PEO) functionalized poly(benzimidazobenzophenanthroline) (BBL) polymers have been prepared by a pulse spray technique on a spinning substrate in ambient atmosphere. The deposition method is advantageous for generating ultra-thin films of nanometer thicknesses. A single spray pulse was found in a reproducible manner to generate a layer of ca. 2 nm thickness. The PEO-chain length in the BBL functionalization had an essential influence on the building mechanism of the films. The polymers functionalized by short PEO chains induced the formation of very smooth films while longer PEO chains induced rough films and notable nanostructuration. The BBL-PEO film deposited using spray pulse deposition was found to be electro- and photoactive. The electron transfer processes observed are slightly different from earlier reported results for similar polymers, which is probably due to the very thin film. The films exhibited photocurrent generation when transformed into conducting form.