Dielectric Characterization of H2O and CO2 Uptake by Polyethylenimine Films

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Abstract

This study investigates the dielectric properties of branched polyethylenimine (PEI) films in relation to their interaction with moisture and CO2. The dielectric measurements were carried out using a non-contact resonant microwave cavity testing method, allowing precise assessment of complex dielectric permittivity as a function of relative humidity (RH) and CO2 content. The addition of CO2 to nitrogen (N2) atmosphere leads to considerable increase in PEI dielectric loss (εr″) with the introduction and subsequent increase in humidity, suggesting enhanced dipolar interactions between CO2 and PEI with the introduction of water. The observed increase in dielectric response with rising RH suggests the introduction of water allows for CO2 uptake through mechanisms leading to charged species in PEI films. Mechanistic hypotheses involving the formation of ionic species, such as carbamate anions and ammonium cations, were proposed to explain the observed dielectric behavior. Overall, this study contributes to the understanding of the dielectric behavior of PEI films in the context of their interaction with H2O and CO2, which is new to applications in carbon sequestration and gas separation technologies

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Materials characterization

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