Chitosan combined with conducting polymers for novel functionality: antioxidant and antibacterial activity Rudolf Kiefer 1a* , Rong-Jer Lee 2b , Rauno Temmer 1c , Tarmo Tamm 1d and Alvo Aabloo 1e 1 University of Tartu, Institute of Technology, Tartu, Estonia 2 Industrial Technology Research Institute, Material and Chemistry Lab, Hsinchu, Taiwan a rudolf.kiefer@ut.ee, b randle@itri.org.tw, c rauno.temmer@ut.ee, d tarmo.tamm@ut.ee, e alvo.aabloo@ut.ee Keywords: Chitosan, PPy, PEDOT, composites, antioxidants, antibacterial 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. 1. Introduction The difficulty in the processability of chemically or electrochemically obtained conducting polymers (CP) lies in their insolubility in aqueous solutions. Chitosan obtained from chitin over N- deacetylation is a natural biopolymer, non-toxic and soluble in light acid, known to show antimicrobial activity [1]. To increase the solubility of chitosan in aqueous media, certain depolymerization techniques are applied to obtain chain-scission with oxidants such as ammonium persulfate (APS) [2], potassium persulfate (PPS) and strong acids. The most common depolymerization agent of chitosan is perhaps sodium nitrite (NaNO 2 ) [3]. Combination of polypyrrole (PPy) with chitosan forms composites soluble in light acids [4]; and the applied oxidant (APS: CPC (Chitosan-PPy composites), NaNO 2 : CPPC, (Chitosan-PPy-Porphyrine composites)) determines which modification of composites are formed. Chemically polymerized PPy in form of powder has been found to be an effective radical scavenger material [5], as shown by the reaction with di(phenyl)-(2,4,6-trinitrophenyl)-iminoazanium (DPPH) radicals. A new synthetic route on chitosan-PEDOT composites (CPTC) has been developed to obtain suspensable composites. The goal of this work is to analyze the conducting polymer chitosan composites in their properties in antioxidant and antibacterial activity in sensor applications [6, 7]. 2. Experimetal 2.1 Chemicals Chitosan (middle molecular weight, 103,000 g mol -1 , deacetylation degree 85%), acetic acid (AA, 97%), sodium nitrite (NaNO 2 ,97%), ammonium peroxydisulfate ((NH 4 ) 2 S 2 O 8 , 98%), ammonium persulfate (APS, 98%), pyrrole (Py, 98%), 3,4 ethylene dioxythiophene (EDOT, 97%), sodium Key Engineering Materials Vol. 605 (2014) pp 428-431 Online available since 2014/Apr/03 at www.scientific.net © (2014) Trans Tech Publications, Switzerland doi:10.4028/www.scientific.net/KEM.605.428 All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP, www.ttp.net. (ID: 90.191.174.155-18/04/14,11:15:14)