Density-functional theory for polymer-carbon dioxide mixtures: a perturbed-chain SAFT approach

Area of Science:

• Physical Chemistry
• Materials Science
• Chemical Engineering

Background:

• Understanding polymer-carbon dioxide mixtures is crucial for applications like gas separation and carbon capture.
• Existing theories often struggle with accurately predicting interfacial properties, especially at high pressures.

Purpose of the Study:

• To develop and validate a new density-functional theory (DFT) for inhomogeneous polymer-carbon dioxide mixtures.
• To improve the prediction of solubility and interfacial tension in polymer-CO2 systems.

Main Methods:

• Utilizing a perturbed-chain statistical associating fluid theory equation of state (PC-SAFT EOS).
• Incorporating fundamental measure theory for inhomogeneous systems and a mean-field approach for dispersion forces.
• Applying the developed DFT to polystyrene-CO2 and poly(methyl methacrylate)-CO2 systems.

Main Results:

• The new DFT accurately predicts solubility and interfacial tension for polymer-CO2 mixtures.
• Achieved quantitative agreement with experimental data for polystyrene-CO2 and poly(methyl methacrylate)-CO2.
• The theory demonstrates improved performance over previous DFT models, particularly at high pressures.

Conclusions:

• The proposed PC-SAFT based DFT offers a robust framework for describing polymer-CO2 mixtures.
• This advanced theory provides superior predictions of interfacial properties compared to earlier models.
• The model overcomes limitations of previous theories, showing reliable behavior even at high pressures.