Papers by Author: Alvo Aabloo

Abstract: Chitosan as a natural biopolymer has applicable functionality for wound healing due to the biocompatible and antibacterial properties. Here we investigate what combined biomimetic functionality can be obtained by forming composites of chitosan and conducting polymers such as polypyrrole (PPy) or poly (3,4-ethylenedioythiophene) (PEDOT). Chemical polymerization shows direct interaction between the chitosan matrix and PPy; such materials can be dissolved as stable suspensions, coated (printed or spin coated) on fabrics or fibers with antioxidant properties of renewable activity. PEDOT and chitosan composites have shown antibacterial properties against staphylococcus aureus. The novel biocompatible chitosan conducting polymer composites will give new direction for obtaining smart materials with diverse functionality, applicable as sensors, food packaging or ion-selective membranes.

Abstract: Composite actuators consisting of sheets of the solid polymer electrolyte (similar to Nafion®) with Cu2+ counter-ions inserted and coated with platinum and copper metal layers (so called Ionomeric Polymer-Metal Composites; IPMC-s) have been synthesized and their electromechanical performance upon actuation has been monitored. Resistivity measurements on the electrodes show that the electrical conductivity of the membranes metal surface increases on the cathode side during the actuation process, contradictory to the situation when Cu is absent from the metal coating. This phenomenon is explained by the subsequent reduction of Cu2+ ions on the cathode upon actuation; Cu layer growth in this side prevents it from cracking and decreases its electrode resistance. The phenomenon opens up for longer life-times for Cu-based IPMC-s. However, additional problems with Cu layer oxidation and Cu dendrite growth on the electrodes should be considered.