Relationship between the gas transport properties and the refractive index in high‐free‐volume fluorine‐containing polyimide membranes

Abstract

The refractive index and gas transport properties (i.e., permeability, diffusivity, and solubility) in the 2,2 0bis(3,4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA)-based polyimides were systematically investigated in terms of their polymer fractional free volumes (FFVs). The permeability and diffusion coefficients of the 6FDA-based polyimide membranes to hydrogen, oxygen, nitrogen, methane, and carbon dioxide were correlated with their FFVs, which were estimated with van Krevelen's group contribution method. Linear correlations were also observed between the gas transport properties and the refractive index of these polyimides. We described FFV as a function of the refractive index based on the Lorentz-Lorenz equation. Linear correlations were observed between their refractive-index-based FFVs and the gas permeability, diffusivity, and solubility coefficients of these 6FDA-based polyimides membranes. However, the FFVs of the 6FDA-based polyimides calculated from refractive index were 1.16-1.37 times larger than their FFV values. This FFV was dependent on the free-volume space and optical factors, such as the refractive index and molar refraction, which affected the electronic structure and the interactions between the gas molecules and the polymer segments.

Optical sensor for hydrogen gas based on a palladium-coated polymer microresonator

“…5a. This corresponds to a very low H 2 detection that can be mainly attributed to the refractive index change in SU-8 as a result of H 2 adsorption [27]. Consistent with the strain caused by the expansion of the Pd layer, a red shift is observed in the WGMs.…”

Substitute Effect of Fluorine-containing Polyimides with Hexafluoroisopropylidene Group on Photo Alignment of Liquid Crystal Molecule

“…The glass-transition temperature values of the isotropic, dense, and non-porous 6FDA-mPD, 6FDA-MPD, 6FDA-TMPD, and 6FDA-TeMPD polyimide films were 298, 335, 380, and 427°C, respectively [8][9][10].…”

“…The 6FDA-based polyimides used in the current research were the same samples which we used in a previous study [8][9][10]. We fabricated isotropic, dense, and nonporous polyimides films through the spin coating method, casting N,N-dimethylacetoamide (Junsei Chemistry Co. Ltd., Tokyo, Japan) solution on the substrates typically at 3500 rpm for 30 s. These 6FDA-based polyimides were baked for 40 min at 180°C to remove the solvents.…”

Photo-reactivities of 6FDA-TeMPD Polyimides Prepared using Different Film Preparation Protocols as an Alignment Layer

“…The 6FDA-TeMPD polyimides used in the current research were the same samples used in a previous study [5,[8][9][10]. The isotopic dense polyimide films were prepared by spin-coating a filtered 2.0 wt% solution of the polymer in highly volatile (boiling point = 67C) tetrahydrofuran (THF, Junsei Chemistry Co. Ltd., Tokyo, Japan) or lowly volatile (boiling point = 166C) N,Ndimethylacetoamide (DMAc, Junsei Chemistry Co. Ltd., Tokyo, Japan) on quartz substrates at 3000 rpm for 30 sec.…”