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DY: Fachverband Dynamik und Statistische Physik
DY 35: Focus Session: Water – from Atmosphere to Space IV (joint session CPP/DY)
DY 35.4: Talk
Wednesday, March 11, 2026, 10:30–10:45, ZEU/0260
Water dynamics in conductive PEDOT:PSS/cellulose nanocomposite films in dependence of relative humidity and temperature — •Lucas Kreuzer1, Marie Betker2, Marcell Wolf1, Jacques Ollivier3, Daniel Söderberg4, and Stephan V. Roth2,4 — 1Heinz Maier-Leibnitz Zentrum (MLZ), TUM, Garching, Germany — 2Deutsches Elektronen Synchrotron, Hamburg, Germany — 3Institut Laue-Langevin, Grenoble, France — 4Department of Engineering Mechanics, Royal Institute of Technology KTH, Stockholm, Sweden
PEDOT:PSS is a conductive and water-soluble polymer blend widely used in organic electronics. However, pure PEDOT:PSS films absorb significant amounts of water, causing swelling, degradation, and eventually a decrease in conductivity. Integrating PEDOT:PSS with cellulose nanofibrils (CNFs) overcomes these issues by limiting water absorption and enhancing mechanical stability. However, a minor amount of water is still absorbed, leading to a change in film morphology: high humidity induces de-wetting of PEDOT:PSS from the CNFs, reducing conductivity, whereas drying generally leads to a re-wetting of PEDOT:PSS, thereby restoring conductivity. To investigate further the role of water, quasi-elastic neutron scattering is applied, which reveals two water species in the films: mobile bulk water and slower hydration water. Upon drying, bulk water is released completely, while hydration water remains in the films, supporting the re-wetting of PEDOT:PSS. Moreover, at higher temperatures, different diffusive behavior was found for bulk and hydration water.
Keywords: water; cellulose; conductive polymer; organic electronics; neutron scattering