Fourier transform infrared spectroscopy investigation of water microenvironments in polyelectrolyte multilayers at varying temperatures
| Autor: | Matthew J. Bolen, Maria Sammalkorpi, Chikaodinaka I. Eneh, Piotr Batys, Pilar C. Suarez-Martinez, Adam L. Bachmann, Michael A. Hickner, Tawanda J. Zimudzi, Jodie L. Lutkenhaus |
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| Přispěvatelé: | Texas A&M University, North Carolina State University, Pennsylvania State University, Polish Academy of Sciences, Department of Chemistry and Materials Science, Department of Bioproducts and Biosystems, Aalto-yliopisto, Aalto University |
| Rok vydání: | 2020 |
| Předmět: |
Materials science
water Enthalpy Analytical chemistry solutions of varying pH 02 engineering and technology General Chemistry 010402 general chemistry 021001 nanoscience & nanotechnology Condensed Matter Physics 01 natural sciences Polyelectrolyte 0104 chemical sciences Polystyrene sulfonate chemistry.chemical_compound chemistry Ionic strength Attenuated total reflection salt Fourier transform infrared spectroscopy 0210 nano-technology Hydrate Spectroscopy |
| Zdroj: | Soft Matter. 16:2291-2300 |
| ISSN: | 1744-6848 1744-683X |
| DOI: | 10.1039/c9sm02478f |
| Popis: | Polyelectrolyte multilayers (PEMs) are thin films formed by the alternating deposition of oppositely charged polyelectrolytes. Water plays an important role in influencing the physical properties of PEMs, as it can act both as a plasticizer and swelling agent. However, the way in which water molecules distribute around and hydrate ion pairs has not been fully quantified with respect to both temperature and ionic strength. Here, we examine the effects of temperature and ionic strength on the hydration microenvironments of fully immersed poly(diallyldimethylammonium)/polystyrene sulfonate (PDADMA/PSS) PEMs. This is accomplished by tracking the OD stretch peak using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy at 0.25-1.5 M NaCl and 35-70 °C. The OD stretch peak is deconvoluted into three peaks: (1) high frequency water, which represents a tightly bound microenvironment, (2) low frequency water, which represents a loosely bound microenvironment, and (3) bulk water. In general, the majority of water absorbed into the PEM exists in a bound state, with little-to-no bulk water observed. Increasing temperature slightly reduces the amount of absorbed water, while addition of salt increases the amount of absorbed water. Finally, a van't Hoff analysis is applied to estimate the enthalpy (11-22 kJ mol-1) and entropy (48-79 kJ mol-1 K-1) of water exchanging from low to high frequency states. |
| Databáze: | OpenAIRE |
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