Regensburg 2025 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 20: Interfaces and Thin Films I

CPP 20.4: Talk

Tuesday, March 18, 2025, 12:30–12:45, H38

Dynamical and morphological changes of polyethylenimine thin films in relation to its CO2 absorption performance — •Maximilian Brückner¹, Martin Tress¹, Soma Ahmadi², and Shiwang Cheng² — ¹Peter Debye Institute for Soft Matter Research, Physics Department, Leipzig University, Germany — ²Department of Chemical Engineering and Materials Science, Michigan State University, United States

Chemical reactions between carbon dioxide (CO2) and amine have been extensively characterized, however, their influence on the dynamics of polyamines remains largely unexplored. In this work, we compare the dynamics of polyethylenimine (PEI) before and after CO2 absorption through broadband dielectric spectroscopy (BDS). The molecular processes of bulk PEI are very different from those of thin film PEI, highlighting an interesting interface and nano-confinement effect. Detailed analyses show CO2 absorption slows down the PEI dynamics, which is consistent with an elevated glass transition temperature of PEI upon CO2 absorption. Further aspects of thin-film-preparation, namely the impact of molecular weight, film thickness, used solvent and plasma treatment of the substrate on surface roughness were investigated by atomic force microscopy and reveal pronounced de-wetting which did not occur in high-molecular-weight PEI on plasma-treated surfaces. The observed changes in dynamics and morphology are likely to reduce the performance of large-scale CO2 capture devices based on low-molecular weight PEI in porous silica, thus suggesting modifications of this approach.

Keywords: Carbon capture; polyethyleneimine (PEI); broadband dielectric spectroscopy; thin polymer films; polymer dynamics