Cellulose nanofibrils (CNF) have proven their strengths in conductive and transparent films. One very promising route for their implementation is the fabrication of porous CNF films in large-industrial scale by spray deposition using water-based technologies; the resulting porous CNF templates are excellent candidates to infiltrate conductive polymers for functionalization. We therefore used poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), widely applied in organic photovoltaics and electronics, to functionalize the porous CNF template. We studied the infiltration, resulting structural rearrangement within the thin CNF film of 400 nm thickness and their behavior under cyclic humidity changes by grazing incidence small-angle neutron scattering (GISANS). Cyclic humidification is reversibly changing the nanoscale structure within the pristine CNF film, which might be attributed to voids or coiling. When infiltrating PEDOT:PSS, the behavior under cyclic humidity changes. Our results indicate the absence of coiling. Hence, morphological changes within the film are inhibited, which might be due to the fact that the polymer completely filled any porous structure within the thin film. Furthermore, we observe selective swelling of the PEDOT:PSS component within the film.<br/><br/>To conclude, we are able to resolve in situ morphological rearrangements within pristine CNF thin films. We showed that this behavior is reversible over at least two humidification cycles. The CNF/PEDOT:PSS composite obtained by infiltration does not show any structural rearrangement, but rather a swelling process. As humidity is present in many device applications and especially during processing and fabrication of conductive CNF composites, our results help to understand the humidity’s nanoscale impact to the meso- or macroscale in a device application.

Conducting polymer infiltration in porous cellulose thin films

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.