Influence of the Composition and Imidization Route on the Chain Packing and Gas Separation Properties of Fluorinated Copolyimides

Abstract

A strong effect of the chemical composition and imidization method on physical and especially on gas transport properties of polyimides was demonstrated. Two fluorinated diamines 6FpDA and bisAPAF were polymerized in different ratios, employing the fluorinated dianhydride 6FDA to get polyimides with nine different compositions. For all synthesized materials three imidization methods were used: azeotropic, thermal, and chemical. The 6FDA-6FpDA homopolymers showed significant differences in the gas transport properties, indicating the influence of the imidization route on the final properties of the polyimides. For polyimides containing bisAPAF, the chemical composition played an important role due to the exchange of the hydroxyl groups by acetate groups leading to different interchain interactions. The gas transport was mainly controlled by the chain packing for thermally and azeotropically imidized polymers with bisAPAF contents lower than 30 mol %. For bisAPAF contents above 50 mol % the gas transport was controlled by the intermolecular interactions, e.g., hydrogen bonds.

Gas Separation Properties of Polyimide Thin Films on Ceramic Supports for High Temperature Applications

“…The 6FDA-6FpDA polyimide was synthesized following the classical in situ silylation two-step method [ 16 ]. A three-necked flask, equipped with a mechanical stirrer and gas inlet and outlet, was charged with 5.0 mmol of the diamine 6FpDA and 5.0 mL of solvent (NMP).…”

Study of the Effect of Inorganic Particles on the Gas Transport Properties of Glassy Polyimides for Selective CO2 and H2O Separation

“…Three different polyimides were employed in the present study: 6FDA-6FpDA, Matrimid ® 5218, and P84 ® . The 6FDA-6FpDA polyimide was synthesized following the classical in-situ silylation two steps method [40]. A detailed description of this synthesis can be found in a previous work [41].…”

“…The permeability, diffusivity and solubility coefficients of CH 4 , CO 2 and H 2 O vapor in the manufactured membranes were determined by using the well-known constant volume, variable pressure method, i.e., the “time-lag method” [40]. The basic principle is the measurement of the transitory response at the downstream part of a membrane to a pressure step at the upstream part, that is, the time-lag ( t 0 ), which is graphically determined as the intersection of the line drawn through the linear region of the pressure increase curve to intersection with the time axis [49].…”

Study of the Effect of Inorganic Particles on the Gas Transport Properties of Glassy Polyimides for Selective CO₂ and H₂O Separation

“…Three different polyimides were employed in the present study: 6FDA-6FpDA, Matrimid ® 5218 and P84 ® . The 6FDA-6FpDA polyimide was synthesized following the classical in-situ silylation two steps method [24]. A detailed description of this synthesis can be found in a previous work [25].…”

“…The permeability, diffusivity and solubility coefficients of CH4, CO2 and H2O vapor in the manufactured membranes were determined by using the well-known constant volume, variable pressure method, i.e. the "time-lag method" [24]. The basic principle is the measurement of the transitory response at the downstream part of a membrane to a pressure step at the upstream part, that is, the time-lag (t0).…”