Prediction of vapor–liquid equilibrium for polymer solutions based on the COSMO‐SAC model

Abstract

To extend the application of the COSMO-SAC model to phase-equilibrium calculations of polymer solutions, a new strategy for estimating the charge-density profile, the cavity volume and the cavity surface area of polymer molecules is proposed by finding reasonable parameters for the corresponding repeating structure units. The molecular parameters for polymers are obtained by summing up the corresponding COSMO calculated values of the repeating units calculated by the algorithms of DMol3 (a density functional theory) or MOPAC (a semi-empirical method). Combining with the COSMO-SAC model, the activities and equilibrium pressures for several typical polymer solutions are satisfactorily predicted indicating that the proposed method can be used for the prediction of vapor-liquid equilibrium of polymer solutions. It was also found that both DMol3 and MOPAC can be used though the results obtained from them are slightly different. The results in this paper show that the method proposed has the potential to predict other phase-equilibrium properties of polymer systems. V

An open and extensible sigma‐profile database for COSMO‐based models

“…One example of COSMO‐based method is the COSMO‐SAC model, a variant of the original COSMO‐RS model . This model has many applications in complex systems, such as the prediction behavior of polymer solution and ionic liquids . In the COSMO‐SAC model, each molecule is described by an apparent surface charge density distribution, determined by the COSMO method.…”

Prediction of sorption in polymers using quantum chemical calculations: Application to polymer membranes

“…They have been applied to a wide range of compounds ranging from simple nonpolar solvents to ionic liquids [35][36][37][38][39][40][41][42] and have shown significant promise in prediction of phase equilibria of these compounds. However, the application of these models to polymer phase equilibria is scarce [43,44], mainly because the quantum chemical calculations for polymers are computationally very intensive.…”

“…Recently, a novel approach has been proposed for application of the Cosmo-SAC and Cosmo-RS models to polymers by carrying out quantum chemical calculations for small oligomers by Yang et al [43] and Goss [44]. In the case of the paper by Goss [44], the Cosmo-RS model is used to predict partition coefficients.…”

“…The approach also cannot be used for the prediction of two component sorption from single component sorption. The approach of Yang et al [43] is more general and it has been applied to vapor sorption over the entire range of thermodynamic activity. However, the approach has been applied only to single component sorption, nonpolar homopolymers and nearly ideal nonpolar systems, and it does not take entanglement or crosslinking of polymer chains into account.…”

“…However, the approach has been applied only to single component sorption, nonpolar homopolymers and nearly ideal nonpolar systems, and it does not take entanglement or crosslinking of polymer chains into account. In this work, we use an approach similar to the one adopted by Yang et al [43] to predict sorption of single component and muticomponent vapors and liquids in nonpolar and polar polymers, and block copolymers involved in membrane separation processes. In addition, we also take into account the entanglement of the polymer chains and the crosslinking of the polymers, which is quite common in polymer membranes, using the Flory-Rehner model.…”