Cloud Point Behavior of Poly(trifluoroethyl methacrylate) in Supercritical CO<sub>2</sub>–Toluene Mixtures

Supercritical CO<sub>2</sub> (scCO<sub>2</sub>) is a versatile solvent for polymer processing; however, many partially fluorinated polymers exhibit limited solubility in neat scCO<sub>2</sub>. Organic cosolvents such as toluene can enhance polymer–solvent interact...

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Main Authors: James R. Zelaya, Gary C. Tepper
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Molecules
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Online Access:https://www.mdpi.com/1420-3049/30/6/1199
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author James R. Zelaya
Gary C. Tepper
author_facet James R. Zelaya
Gary C. Tepper
author_sort James R. Zelaya
collection DOAJ
description Supercritical CO<sub>2</sub> (scCO<sub>2</sub>) is a versatile solvent for polymer processing; however, many partially fluorinated polymers exhibit limited solubility in neat scCO<sub>2</sub>. Organic cosolvents such as toluene can enhance polymer–solvent interactions, thereby improving solubility. The cloud point behavior of poly(2,2,2-trifluoroethyl methacrylate) (poly(TFEMA)) at 3 wt% concentration in scCO<sub>2</sub>–toluene binary mixtures was investigated over a temperature range of 31.5–50 °C and toluene contents of 0–20 wt%. Solvent mixture densities were estimated using the Altuin–Gadetskii–Haar–Gallagher–Kell (AG–HGK) equation of state for CO<sub>2</sub> and the Tait equation for toluene. For all compositions, the cloud point pressure was observed to increase linearly with temperature. The cloud point pressure decreased monotonically with increasing toluene concentration and at the highest concentration of 20 wt% was reduced by approximately 40% in comparison to neat scCO<sub>2</sub>. The addition of toluene lowered the solvent density, but the increase in solvent–solute molecular interactions resulted in the observed decrease in cloud point pressure. Toluene is shown to be an effective cosolvent for dissolving poly(TFEMA) in scCO<sub>2</sub>, offering a promising approach to lowering operating pressures in fluoropolymer processing. Our results provide valuable phase behavior data for designing scCO<sub>2</sub>-based extraction, impregnation, and particle formation processes involving poly(TFEMA).
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spelling doaj-art-9fb85e34cfdf4e4182c43973ed11e0612025-08-20T02:42:22ZengMDPI AGMolecules1420-30492025-03-01306119910.3390/molecules30061199Cloud Point Behavior of Poly(trifluoroethyl methacrylate) in Supercritical CO<sub>2</sub>–Toluene MixturesJames R. Zelaya0Gary C. Tepper1Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University (VCU), Richmond, VA 23284, USADepartment of Mechanical and Nuclear Engineering, Virginia Commonwealth University (VCU), Richmond, VA 23284, USASupercritical CO<sub>2</sub> (scCO<sub>2</sub>) is a versatile solvent for polymer processing; however, many partially fluorinated polymers exhibit limited solubility in neat scCO<sub>2</sub>. Organic cosolvents such as toluene can enhance polymer–solvent interactions, thereby improving solubility. The cloud point behavior of poly(2,2,2-trifluoroethyl methacrylate) (poly(TFEMA)) at 3 wt% concentration in scCO<sub>2</sub>–toluene binary mixtures was investigated over a temperature range of 31.5–50 °C and toluene contents of 0–20 wt%. Solvent mixture densities were estimated using the Altuin–Gadetskii–Haar–Gallagher–Kell (AG–HGK) equation of state for CO<sub>2</sub> and the Tait equation for toluene. For all compositions, the cloud point pressure was observed to increase linearly with temperature. The cloud point pressure decreased monotonically with increasing toluene concentration and at the highest concentration of 20 wt% was reduced by approximately 40% in comparison to neat scCO<sub>2</sub>. The addition of toluene lowered the solvent density, but the increase in solvent–solute molecular interactions resulted in the observed decrease in cloud point pressure. Toluene is shown to be an effective cosolvent for dissolving poly(TFEMA) in scCO<sub>2</sub>, offering a promising approach to lowering operating pressures in fluoropolymer processing. Our results provide valuable phase behavior data for designing scCO<sub>2</sub>-based extraction, impregnation, and particle formation processes involving poly(TFEMA).https://www.mdpi.com/1420-3049/30/6/1199scCO<sub>2</sub>poly(trifluoroethyl methacrylate) (poly(TFEMA))cosolventtoluenecloud pointphase behavior
spellingShingle James R. Zelaya
Gary C. Tepper
Cloud Point Behavior of Poly(trifluoroethyl methacrylate) in Supercritical CO<sub>2</sub>–Toluene Mixtures
Molecules
scCO<sub>2</sub>
poly(trifluoroethyl methacrylate) (poly(TFEMA))
cosolvent
toluene
cloud point
phase behavior
title Cloud Point Behavior of Poly(trifluoroethyl methacrylate) in Supercritical CO<sub>2</sub>–Toluene Mixtures
title_full Cloud Point Behavior of Poly(trifluoroethyl methacrylate) in Supercritical CO<sub>2</sub>–Toluene Mixtures
title_fullStr Cloud Point Behavior of Poly(trifluoroethyl methacrylate) in Supercritical CO<sub>2</sub>–Toluene Mixtures
title_full_unstemmed Cloud Point Behavior of Poly(trifluoroethyl methacrylate) in Supercritical CO<sub>2</sub>–Toluene Mixtures
title_short Cloud Point Behavior of Poly(trifluoroethyl methacrylate) in Supercritical CO<sub>2</sub>–Toluene Mixtures
title_sort cloud point behavior of poly trifluoroethyl methacrylate in supercritical co sub 2 sub toluene mixtures
topic scCO<sub>2</sub>
poly(trifluoroethyl methacrylate) (poly(TFEMA))
cosolvent
toluene
cloud point
phase behavior
url https://www.mdpi.com/1420-3049/30/6/1199
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