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Investigation of the degree of homogeneity and hydrogen bonding in PEG/PVP blends prepared in supercritical CO2: Comparison with ethanol-cast blends and physical mixtures

Abstract
The degree of homogeneity and H-bond interaction in blends of low-molecular-mass poly(ethylene
glycols) (PEG, Mw = 400, 600, 1000) and poly(vinylpyrrolidone) (PVP, Mw =9×103) prepared in supercritical
CO2, ethanol and as physical mixtures were studied by differential scanning calorimetry (DSC),
Fourier-transform infrared (FTIR) spectroscopy and dynamic mechanical analysis (DMA) techniques.
Homogeneity of samples prepared in supercritical CO2 were greater than physically mixed samples,
but slightly less than ethanol-cast samples. PEG–PVP H-bond interaction was higher for ethanol-cast
blends when compared to blends prepared in supercritical CO2. This reduced interaction was attributed
to a combination of: (1) shielding of PEG–PVP H-bond interactions when CO2 is dissolved in the blend;
(2) rapidly reduced PEG and PVP chain mobility upon CO2 venting, delaying rearrangement for optimum
PEG–PVP H-bond interaction.

Identiferoai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:tut/oai:encore.tut.ac.za:d1002009
Date04 February 2010
CreatorsLabuschagne, PW, John, MJ, Sadiku, RE
PublisherElsevier
Source SetsSouth African National ETD Portal
LanguageEnglish
Detected LanguageEnglish
TypeText
FormatPdf
Rights© 2010 Elsevier B.V.
RelationThe Journal of Supercritical Fluids

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