Fatty acid aggregation in supercritical carbon dioxide

Miller, Douglas A.; Clark, Douglas S.; Blanch, Harvey W.; Prausnitz, John M.

doi:10.1016/0896-8446(91)90040-d

Cited by 9 publications

(1 citation statement)

References 5 publications

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“…EPR makes it possible to evaluate the mobility of a probe on multiple spatial scales [ 50 ]: rotational mobility is readily obtained from the shape of the EPR spectrum, molecular-scale translational mobility (<10 nm path) can be obtained by exchange interaction rate measurement, and, finally, EPR imaging and probe uptake measurement deliver macroscopic diffusivity. High-pressure/in situ EPR spectroscopy uses equipment similar to that of high-pressure NMR [ 51 ], and has been used so far to evaluate density enhancement and exchange reactions in SCFs [ 52 , 53 , 54 , 55 , 56 , 57 ], clustering of the solute in SCFs [ 58 , 59 , 60 , 61 , 62 ], microemulsion formation [ 63 , 64 ], and glass transition pressure in polylactide and polylactide-co-glycolide subjected to subcritical CO 2 [ 48 ]. In addition, it has been reported that the mobility of spin probes can reflect the distribution of free volume in polymers plasticized by subcritical CO 2 , similar to a conventional plasticizer [ 49 ].…”

Section: Introductionmentioning

confidence: 99%

Solute Diffusion into Polymer Swollen by Supercritical CO2 by High-Pressure Electron Paramagnetic Resonance Spectroscopy and Chromatography

et al. 2021

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High-pressure electron paramagnetic resonance (EPR) was used to measure translational diffusion coefficients (Dtr) of a TEMPONE spin probe in poly(D,L-lactide) (PDLLA) and swollen in supercritical CO2. Dtr was measured on two scales: macroscopic scale (>1 μm), by measuring spin probe uptake by the sample; and microscopic scale (<10 nm), by using concentration-dependent spectrum broadening. Both methods yield similar translational diffusion coefficients (in the range 5–10 × 10−12 m2/s at 40–60 °C and 8–10 MPa). Swollen PDLLA was found to be homogeneous on the nanometer scale, although the TEMPONE spin probe in the polymer exhibited higher rotational mobility (τcorr = 6 × 10−11 s) than expected, based on its Dtr. To measure distribution coefficients of the solute between the swollen polymer and the supercritical medium, supercritical chromatography with sampling directly from the high-pressure vessel was used. A distinct difference between powder and bulk polymer samples was only observed at the start of the impregnation process.

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Section: Introductionmentioning

confidence: 99%

Solute Diffusion into Polymer Swollen by Supercritical CO2 by High-Pressure Electron Paramagnetic Resonance Spectroscopy and Chromatography

et al. 2021

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Near‐infrared spectroscopic investigations on phase behaviour and hydrogen‐bonding of polar substances in supercritical chlorotrifluoromethane. Part II — association behaviour

Ochel

Schneider

1994

Ber Bunsenges Phys Chem

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The association behaviour of selected polar substances capable of self-association in mixtures with supercritical chlorotrifluoromethane was investigated by high-pressure near-infrared spectroscopy. The alkanoic acids and cyclic amides investigated were dodecanoic acid, hexadecanoic acid, Gvalerolactam, and &-caprolactam. The concentrations of the non-associated molecules were determined from an evaluation of the first overtone region of 0 --H ( -1435 nm) or N-H stretching vibrations ( -1485 nm), respectively. The association behaviour is presented in plots of total, free, and hydrogen-bonded molecule concentrations as a function of pressure. Furthermore, equilibrium constants K, were determined and their density dependence is discussed, taking into account the influence of molecular properties on the association reaction in the supercritical fluid.

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FTIR study of hydrogen bonding of stearic acid with ethanol, dimethyl sulfoxide, and acetonitrile in supercritical CO₂

Mao

Lü

et al. 1999

Chin. J. Chem.

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Articles FTIR study of hydrogen bonding of stearic acid with ethanol, dimethyl sulfoxide, and acetonitrile in supercritical CO,? Ahstmet F I z R s~~m t e u s e d t o s t u d y t h e h~b o n~o f s t e a d c a c~d~~e t h a n a l , dimethyl sulfoxide (DMSO), and acetonitde in supercritical CQ at 318.15 K, and 12.5 and 16.5 MF'a. ?he concentmtiom ofthe codvents range from0-0.6 d -L -' . ?he area percentage of absorption bands for hydmgm-bonded and nonhydrogen-bonded species was ObtainedfrOmthelRspectra. The acid and the cosalventscanformhydrogen bond even when their concentrations a very low. At hed d u t e concentration, the extent of hydmgen bondmg increases with oosolvent concentration. At higher ethanol concentratim, it seem9 that one e&c acid molecule can hydmgen bond with more than one ethanol molecules s i m u l~y .It is seen that the stxengh of the hy+n bond formed by the acid and the cosolvents is in the order: DMSO > ethanol > acetonit.de.

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Fatty acid aggregation in supercritical carbon dioxide

Cited by 9 publications

References 5 publications

Solute Diffusion into Polymer Swollen by Supercritical CO2 by High-Pressure Electron Paramagnetic Resonance Spectroscopy and Chromatography

Solute Diffusion into Polymer Swollen by Supercritical CO2 by High-Pressure Electron Paramagnetic Resonance Spectroscopy and Chromatography

Near‐infrared spectroscopic investigations on phase behaviour and hydrogen‐bonding of polar substances in supercritical chlorotrifluoromethane. Part II — association behaviour

FTIR study of hydrogen bonding of stearic acid with ethanol, dimethyl sulfoxide, and acetonitrile in supercritical CO₂

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Fatty acid aggregation in supercritical carbon dioxide

Cited by 9 publications

References 5 publications

Solute Diffusion into Polymer Swollen by Supercritical CO2 by High-Pressure Electron Paramagnetic Resonance Spectroscopy and Chromatography

Solute Diffusion into Polymer Swollen by Supercritical CO2 by High-Pressure Electron Paramagnetic Resonance Spectroscopy and Chromatography

Near‐infrared spectroscopic investigations on phase behaviour and hydrogen‐bonding of polar substances in supercritical chlorotrifluoromethane. Part II — association behaviour

FTIR study of hydrogen bonding of stearic acid with ethanol, dimethyl sulfoxide, and acetonitrile in supercritical CO2

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FTIR study of hydrogen bonding of stearic acid with ethanol, dimethyl sulfoxide, and acetonitrile in supercritical CO₂