Prediction of Phase Behaviors of Polymer–Solvent Mixtures from the COSMO-SAC Activity Coefficient Model

Abstract

An efficient method for prediction of the vapor−liquid and liquid−liquid phase behaviors of polymer−solvent mixtures is proposed using the COSMO-SAC activity coefficient model. In particular, we examine various approaches for generating the screening charge distribution of homepolymers and copolymers from quantum mechanical calculations and propose a novel method to generate such data efficiently using a finite number of repeating units. The free volume effects known to be important in polymer solutions are considered through the free volume model of Elbro and co-workers. We have examined this model using 2249 vapor−liquid equilibria data points from 25 homopolymers, 8 copolymers, and 48 solvents. The overall average deviation (AAD%) of solvent activity is found to be about 16%, which is comparable to that from other UNIFAC-based models. The liquid−liquid equilibrium of polymer−solvent mixtures can be predicted in qualitative agreement with experiment. The proposed method is capable of describing the changes in solvent activity due to temperature, polymer molecular weight, and polymer tacticity. Our results suggest that the proposed method is a useful complementary to group contribution method for phase behavior of polymer solutions when group parameter or density information of polymers is unavailable.

A Benchmark Open-Source Implementation of COSMO-SAC

“…Fingerhut et al examined thoroughly its performance for over ten thousand binary mixtures based on 2295 compounds, including water. 25 The method can also be used for polymers 26 and, when combined with the Pitzer-Debye-Hückel model, for electrolyte 27,28 and ionic liquids. 29,30 The article is organized thematically by addressing the following aspects of the COSMO-SAC model: The COSMO file obtained as the output of a quantum mechanical density-functional-theory calculation is a text file of non-standardized format containing the results of the calculation and information about the molecule.…”

Extraction performance evaluation and theoretical analysis of removal of phenol from oil mixture using a dual‐functionalized ionic liquid: 1‐hydroxyethyl‐3‐methylimidazolium propionate

“…The DMol3 in Materials Studio was implemented 30 to calculate the interaction energy, bond length and electron density between the IL and organic components. 31 The COSMO-SAC model was applied to calculate the ⊞-profile.…”

Separation of ethyl acetate and 2-propanol azeotropic mixture using ionic liquids as entrainers

“…Firstly, all optimized geometries were obtained by minimizing the total energy of the molecule in the ideal gas phase (no imaginary frequency) using the density functional theory with the VWN-BP functional and version 4.0.0 DNP basis set by employing the DMol3 module implemented in MS. [27] Then, COSMO calculation was conducted to gain the parameters, such as the molecular volume, surface area and screening charges. [28] Finally, the .COSMO files were imported into the calculating software (Sigma-average_v2.exe) to obtain the data forσ-Profiles.…”