Optical characterization of co-nonsolvency effects in thin responsive PNIPAAm-based gel layers exposed to ethanol/water mixtures

Ilke Anac; Alena Aulasevich; Matthias J N Junk; Piotr Jakubowicz; Robert F Roskamp; Bernhard Menges; Ulrich Jonas; Wolfgang Knoll

doi:10.1002/macp.200900533

Optical characterization of co-nonsolvency effects in thin responsive PNIPAAm-based gel layers exposed to ethanol/water mixtures

Ilke Anac, Alena Aulasevich, Matthias J N Junk, Piotr Jakubowicz, Robert F Roskamp, Bernhard Menges, Ulrich Jonas, Wolfgang Knoll

Department of Chemistry

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36 Citations (SciVal)

Abstract

Surface-attached, photo-crosslinked gel films of a N-isopropylacrylamide copolymer were investigated in ethanol/water mixtures using a combination of surface plasmon resonance/ optical waveguide spectroscopy with reversed WKB analysis. The solvent quality of the pure good solvents drops in their mixture and this co- nonsolvency effect shifts the transition temperature (T c) in the μm-thin gel films from 32.8 °Cin pure water to 29.7 °C with only 0.25 vol.-% etha- nol. Between 20 and 70% ethanol and >10 °C (the practical temperature limit) the layers existed only in the collapsed state. A reentrant Tc of 40.2 °C was found at 70% ethanol while at higher ethanol volume fraction no Tc could be recorded.

Original language	English
Pages (from-to)	1018-1025
Number of pages	8
Journal	Macromolecular Chemistry and Physics
Volume	211
Issue number	9
DOIs	https://doi.org/10.1002/macp.200900533
Publication status	Published - 3 May 2010

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title = "Optical characterization of co-nonsolvency effects in thin responsive PNIPAAm-based gel layers exposed to ethanol/water mixtures",

abstract = "Surface-attached, photo-crosslinked gel films of a N-isopropylacrylamide copolymer were investigated in ethanol/water mixtures using a combination of surface plasmon resonance/ optical waveguide spectroscopy with reversed WKB analysis. The solvent quality of the pure good solvents drops in their mixture and this co- nonsolvency effect shifts the transition temperature (T c) in the μm-thin gel films from 32.8 °Cin pure water to 29.7 °C with only 0.25 vol.-% etha- nol. Between 20 and 70% ethanol and >10 °C (the practical temperature limit) the layers existed only in the collapsed state. A reentrant Tc of 40.2 °C was found at 70% ethanol while at higher ethanol volume fraction no Tc could be recorded.",

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T1 - Optical characterization of co-nonsolvency effects in thin responsive PNIPAAm-based gel layers exposed to ethanol/water mixtures

AU - Anac, Ilke

AU - Aulasevich, Alena

AU - Junk, Matthias J N

AU - Jakubowicz, Piotr

AU - Roskamp, Robert F

AU - Menges, Bernhard

AU - Jonas, Ulrich

AU - Knoll, Wolfgang

PY - 2010/5/3

Y1 - 2010/5/3

N2 - Surface-attached, photo-crosslinked gel films of a N-isopropylacrylamide copolymer were investigated in ethanol/water mixtures using a combination of surface plasmon resonance/ optical waveguide spectroscopy with reversed WKB analysis. The solvent quality of the pure good solvents drops in their mixture and this co- nonsolvency effect shifts the transition temperature (T c) in the μm-thin gel films from 32.8 °Cin pure water to 29.7 °C with only 0.25 vol.-% etha- nol. Between 20 and 70% ethanol and >10 °C (the practical temperature limit) the layers existed only in the collapsed state. A reentrant Tc of 40.2 °C was found at 70% ethanol while at higher ethanol volume fraction no Tc could be recorded.

AB - Surface-attached, photo-crosslinked gel films of a N-isopropylacrylamide copolymer were investigated in ethanol/water mixtures using a combination of surface plasmon resonance/ optical waveguide spectroscopy with reversed WKB analysis. The solvent quality of the pure good solvents drops in their mixture and this co- nonsolvency effect shifts the transition temperature (T c) in the μm-thin gel films from 32.8 °Cin pure water to 29.7 °C with only 0.25 vol.-% etha- nol. Between 20 and 70% ethanol and >10 °C (the practical temperature limit) the layers existed only in the collapsed state. A reentrant Tc of 40.2 °C was found at 70% ethanol while at higher ethanol volume fraction no Tc could be recorded.

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Optical characterization of co-nonsolvency effects in thin responsive PNIPAAm-based gel layers exposed to ethanol/water mixtures

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