Small-Angle X-ray Scattering Insights into the Architecture-Dependent Emulsifying Properties of Amphiphilic Copolymers in Supercritical Carbon Dioxide

In order to obtain F-III fibers with high mechanical properties, pristine F-III fibers were hot drawn at the temperature of 250 °C, pressure of 14 MPa, tension of 6 g·d−1, and different times, which were 15 min, 30 min, 45 min, 60 min, 75 min, 90 min, and 105 min, respectively, in supercritical carbon dioxide (Sc-CO2) in this article. All the samples, including the pristine and treated F-III fibers, were characterized by a mechanical performance tester, wide-angle X-ray scattering (WAXS), small-angle X-ray scattering (SAXS), and thermogravimetric analysis (TGA). The results showed that the thermal stability of F-III fibers was enhanced to some extent, and the tensile strength and modulus of F-III fibers had great changes as the extension of treatment time during hot drawing in Sc-CO2, although the treatment temperature was lower than the glass transition temperature (Tg) of F-III fibers. Accordingly, the phase fraction, orientation factor fc of the (110) crystal plane, fibril length lf, and misorientation angle Bφ of all the samples were also investigated. Fortunately, the hot drawing in Sc-CO2 was successfully applied to the preparation of F-III fibers with high mechanical properties.

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Effect of Different Pressures on Microstructure and Mechanical Performance of F-III Fibers in Supercritical Carbon Dioxide Fluid

Materials ◽

10.3390/ma12050690 ◽

2019 ◽

Vol 12 (5) ◽

pp. 690 ◽

Cited By ~ 2

Author(s):

Xiaoma Ding ◽

Haijuan Kong ◽

Mengmeng Qiao ◽

Zhifeng Hu ◽

Muhuo Yu

Keyword(s):

Carbon Dioxide ◽

Supercritical Carbon Dioxide ◽

Mechanical Performance ◽

Treatment Temperature ◽

Orientation Factor ◽

X Ray ◽

X Ray Scattering ◽

Fibril Length ◽

Supercritical Carbon ◽

Ray Scattering

F-III fibers were treated at different pressures in supercritical carbon dioxide fluid and all samples including untreated and treated F-III fibers were characterized by a mechanical performance tester, wide-angle X-ray scattering and small-angle X-ray scattering. By studying the relationship between mechanical performance and microstructural changes of the samples, it was found that microstructural change was the main cause of variation in mechanical performance. Results revealed that the maximum tensile strength and modulus of F-III fibers were acquired at 14 MPa within the pressure range of 8 MPa to 16 MPa when the temperature, tension and time were 250 °C, 6 g·d−1 and 40 min, respectively. Correspondingly, the microstructures of the samples, including the phase fraction, crystal size, orientation factor, fibril radius, fibril length and misorientation angle, have been investigated. It was fortunate that the supercritical carbon dioxide fluid could be used as a medium during the hot-stretch process to improve the mechanical performance of F-III fibers, although the treatment temperature was lower than the glass transition temperature of the F-III fibers.

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Homogeneous nucleation of carbon dioxide in supersonic nozzles I: experiments and classical theories

Physical Chemistry Chemical Physics ◽

10.1039/d0cp02279a ◽

2020 ◽

Vol 22 (34) ◽

pp. 19282-19298

Author(s):

Kayane K. Dingilian ◽

Roope Halonen ◽

Valtteri Tikkanen ◽

Bernhard Reischl ◽

Hanna Vehkamäki ◽

...

Keyword(s):

Carbon Dioxide ◽

Small Angle ◽

Homogeneous Nucleation ◽

Pressure Measurements ◽

Supersonic Nozzles ◽

X Ray ◽

X Ray Scattering ◽

Ray Scattering

Small angle X-ray scattering and pressure measurements yield quantitative homogeneous nucleation rates for CO2 near 80 K.

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Small-Angle X-ray Scattering Measurements of Ionic Liquids Pressurized with Carbon Dioxide Using Titanium Sample Holder: 1-Butyl-3-methylimidazolium Bis(trifluoromethylsulfonyl) Amide Mixtures up to 22 MPa

Japanese Journal of Applied Physics ◽

10.1143/jjap.51.076703 ◽

2012 ◽

Vol 51 ◽

pp. 076703 ◽

Cited By ~ 2

Author(s):

Takeshi Morita ◽

Masayoshi Ushio ◽

Kaori Kanoh ◽

Eiichi Tanaka ◽

Keiko Nishikawa

Keyword(s):

Carbon Dioxide ◽

Ionic Liquids ◽

Small Angle ◽

Sample Holder ◽

Titanium Sample ◽

X Ray ◽

X Ray Scattering ◽

Scattering Measurements ◽

Ray Scattering

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Thermodynamic Nature of Monodisperse Polystyrene in Mixed Solvent of Cyclohexane and Antisolvent Carbon Dioxide Using Synchrotron Small-Angle X-ray Scattering

Macromolecules ◽

10.1021/ma021293e ◽

2002 ◽

Vol 35 (27) ◽

pp. 10114-10118 ◽

Cited By ~ 2

Author(s):

Dan Li ◽

Zhimin Liu ◽

Buxing Han ◽

Guanying Yang ◽

Liping Song ◽

...

Keyword(s):

Carbon Dioxide ◽

Small Angle ◽

Mixed Solvent ◽

X Ray ◽

X Ray Scattering ◽

Monodisperse Polystyrene ◽

Ray Scattering

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The Morphology of Block Copolymer Micelles in Supercritical Carbon Dioxide by Small-Angle Neutron and X-ray Scattering

Journal of Applied Crystallography ◽

10.1107/s0021889897002446 ◽

1997 ◽

Vol 30 (5) ◽

pp. 690-695 ◽

Cited By ~ 24

Author(s):

J. D. Londono ◽

R. Dharmapurikar ◽

H. D. Cochran ◽

G. D. Wignall ◽

J. B. McClain ◽

...

Keyword(s):

Carbon Dioxide ◽

Block Copolymer ◽

Small Angle ◽

X Ray ◽

X Ray Scattering ◽

Environmentally Responsible ◽

Theoretical Predictions ◽

Block Copolymer Micelles ◽

Copolymer Micelles ◽

Ray Scattering

Above its critical point, carbon dioxide forms a super-critical fluid, which promises to be an environmentally responsible replacement for the organic solvents traditionally used in polymerizations. Many lipophilic polymers such as polystyrene (PS) are insoluble in CO2, though polymerizations may be accomplished via the use of PS-fluoropolymer stabilizers, which act as emulsifying agents. Small-angle neutron and X-ray scattering have been used to show that these molecules form micelles with a CO2-phobic PS core and a CO2-philic fluoropolymer corona. When the PS block was fixed in length and the fluorinated corona block was varied, the number of block copolymer molecules per micelle (six to seven) remained constant. Thus, the coronal block molecular weight exerts negligible influence on the aggregation number, in accordance with the theoretical predictions of Halperin, Tirrell & Lodge [Adv. Polym. Sci. (1992), 100, 31–46]. These observations are relevant to understanding the mechanisms of micellization and solubilization in supercritical fluids.

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