ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

A molecular dynamics simulation study on the solubilities of monomers of a PIM-1 polymer in supercritical carbon dioxide

Niloufar Saadatkish, Javad Karimi-Sabet, and Alireza Sharif

Polymer Reaction Engineering Department, Faculty of Chemical Engineering, Tarbiat Modares University, Tehran, Iran

E-mail: jvkarimi@nstri.ir

Received: 9 June 2021  Accepted: 28 December 2021

Abstract:

Abstract

The absolute solubilities of tetrahydroxy-3,3,3′,3′-tetramethyl-1,1′-spirobisindane (TTSBI) and tetrafluoroterephthalonitrile (TFTPN), the monomers of a polymer of intrinsic microporosity-1 (PIM-1), in supercritical carbon dioxide (SCCO₂), are studied by molecular dynamics (MD) simulation method. Solvation free energies of the monomers in SCCO₂ are simulated at different temperatures and pressures by the thermodynamic integration method. Furthermore, a new procedure is proposed to calculate the external pressure dependency of the monomers vapor pressures by MD simulation. These two quantities are used to estimate the absolute solubility of each monomer in SCCO₂ medium. TFTPN showed higher solubility (than TTSBI) which was ascribed to its CO₂-philic structure and low vapor pressure. Experimentally measured solubilities are in good agreement with the simulated ones confirming the accuracy of the proposed method for the calculation of vapor pressures. Finally, SCCO₂ medium is suggested as a suitable medium for synthesis of PIM-1 polymer provided that small amounts of a cosolvent are used or high external pressures (greater than 30 MPa) are applied.

Graphical abstract

Keywords: Tetrahydroxy-3,3,3′,3′-tetramethyl-1,1′-spirobisindane (TTSBI); Tetrafluoroterephthalonitrile (TFTPN); Supercritical carbon dioxide; Absolute solubility; Molecular dynamic (MD) simulation

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-021-02051-6

Chemical Papers 76 (5) 2981–2989 (2022)