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Please use this identifier to cite or link to this item: http://hdl.handle.net/10204/4941

Title: In situ FTIR spectroscopic study of the effect of CO2 sorption on H-bonding in PEG–PVP mixtures
Authors: Labuschagne, PW
Kazarian, SG
Sadiku, RE
Keywords: Supercritical fluids
ATR
FTIR spectroscopy
H-bond
Polymer blends
Molecules
Biomolecular spectroscopy
Issue Date: May-2011
Publisher: Elsevier Publishers
Citation: Labuschagne, PW, Kazarian, SG, and Sadiku, RE. 2011. In situ FTIR spectroscopic study of the effect of CO2 sorption on H-bonding in PEG–PVP mixtures. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Vol. 78(5), pp 1500-1506
Series/Report no.: Workflow;6195
Abstract: A study of the H-bonding between poly(ethylene glycol) (PEG) and polyvinylpyrrolidone (PVP) in the presence of supercritical carbon dioxide at various temperatures, pressures, different M(w) of PEG and PVP and different PEG/PVP ratios is presented. In situ attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy was used to investigate H-bonding by examining changes in the relative intensities and positions of peak maxima of the 2nd derivative (CO) bands associated with 'free' and H-bonded CO groups. In general, relative intensities of bands associated with H-bonded CO groups decreased upon CO(2) sorption and was accompanied by an increase in intensity of bands associated with 'free' CO groups. At the same time, these bands were shifted to higher wavenumbers. These shifts were attributed to the shielding effect of CO(2) molecules on H-bonding interactions between PEG and PVP. The magnitude of the effects of CO(2) shielding generally increased with decreasing polymer M(w) and increasing CO(2) content. However, upon CO(2) venting the extent of the H-bonding between PEG and PVP reappeared. The extent of H-bonding recovery was greatest for blends with low M(w) PEG (M(w): 4×10(2)) and PVP (M(w): 9×10(3)) and PEG content =0.54wt% under mild conditions of pressure (80bar) and temperature (35°C). For the same low M(w) blends, increasing pressure to 150bar, or temperature to 50°C, showed poor H-bond recovery upon CO(2) venting. Overall, it was shown that supercritical CO(2)-induced shielding of H-bonding interactions in polymer blends is reversible upon CO(2) venting, and the magnitude of both was influenced by processing conditions and blend composition.
Description: Copyright: 2011 Elsevier. This is the post print version of the work. The definitive version is published in Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Vol. 78(5), pp 1500-1506
URI: http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6VNG-5236RJC-3-2&_cdi=6178&_user=958262&_pii=S1386142511000679&_origin=gateway&_coverDate=05%2F31%2F2011&_sk=999219994&view=c&wchp=dGLbVtz-zSkzV&md5=96f0016045b9a31921b7cf1d8ddbd8c5&ie=/sdarticle.pdf
http://hdl.handle.net/10204/4941
ISSN: 1386-1425
Appears in Collections:Polymers and composites
Analytical science
General science, engineering & technology

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