Anna-Liisa Peikolainen

Organic acid catalyzed synthesis of 5-methylresorcinol based organic aerogels in acetonitrile

A method of preparing 5-methylresorcinol and formaldehyde based organic aerogels in non-aqueous media with a benzoic acid derivative as a catalyst is being proposed in this paper. Here acetonitrile is used as a solvent that allows direct drying with carbon dioxide over the supercritical state without the need for a solvent exchange. The acidic properties of 2,6-dihydroxy-4-methyl benzoic acid promote the reaction of sol–gel polymerization, and at the same time it takes part in the reaction as a co-monomer and influences the nanostructure of the material. The evolution of the polymer was monitored using nuclear magnetic resonance spectroscopy and the structure of the resulting organic aerogels depending on the molar ratio of 5-methylresorcinol to 2,6-dihydroxy-4-methyl benzoic acid was studied by nitrogen adsorption–desorption measurements, scanning electron microscopy and infrared spectrometry.

Solvent and electrolyte effects in PPyDBS free standing films

Free standing conducting polymer films based on polypyrrole doped with dodecylbenzoesulfate (PPyDBS) are investigated in TBACF3SO3 (tetrabutylammonium trifluoromethanesulfonate) propylene carbonate (PC-Tf) followed in aqueous TMACl tetramethylammonium chloride (Aq-TM) with the aim to investigate actuation properties (anion or cation-driven actuation). Under isometric (constant force) conditions ECMD (electro-chemo-mechanical deformation) measurements are performed during cyclic voltammetric and chronoamperometric experiments. Electrolyte and solvent effects revealing that the actuation direction in propylene carbonate electrolyte changed from expansion at anodic potential to expansion at cathodic potentials during square wave potential steps. Finally if the PPyDBS film immersed in aqueous electrolyte the anion-driven actuation properties are maintenance. SEM measurements are implemented to reefer changes in film morphology and ion content (EDX, energy dispersive X-Ray) before and after actuation.

Fabrication of ion-conducting carbon-polymer composite electrodes by spin-coating

We report a fabricating method for ion-conducting carbon electrodes on top of industrially produced PVDF membrane by spin-coating. Spin-coating is desirable due to its potential application in large-scale actuator manufacturing and its possibility to produce very thin electrodes. The industrial grade membrane was chosen in order to investigate more accurately the results of spin-coating without considering the deviations present in a hand-made membrane. Spin-coating and surface resistivity measurements via four-point probe were described in further detail. The production process of electrode suspension and suspension dispensing were developed and fine-tuned. The spin coater was programmed to obtain electrodes with uniform electrical properties. The arrangement of the spin coater was slightly altered to remove swelling and bubble formation effects concurrent with usage of the porous membrane. Electrodes produced with the developed method were measured and analyzed. Thickness of the film was measured with micrometer screw gauge and four-point probe was used to measure sheet resistivity, in addition film was studied under scanning electron microscope. In best cases the coefficient of variation for sheet conductivity was 6.2%. For all electrode sheet conductivities the median coefficient of variation was 7%. The thickness of the electrodes varied from 6 to 23 μm. As a proof of concept for the developed method a working actuator with spin-coated electrodes was produced.