Density functional approach for modeling $CO2$ pressurized polymer thin films in equilibrium

We have used polymer density functional theory to analyze the equilibrium density profiles and interfacial properties of thin films of polymer in the presence of $CO2$⁠. Surface tension, surface excess adsorption of $CO2$ on polymer surface, and width of the interface are discussed. We have shown the changes in these properties in the presence of $CO2$ and with increasing film thickness and their inverse linear relationship with increasing chain length. One of our important findings is the evidence of segregation of end segments toward the interface. We have introduced a new method of representing this phenomenon by means of $Δ$ profiles that show increase in segregation owing to the presence of $CO2$ and with increasing chain length. We also make predictions for the octacosane-$CO2$ binary system near the critical point of $CO2$⁠. Our results indicate qualitative trends that are comparable to the similar experimental and simulation studies.