Polyimides Containing Phosphaphenanthrene Skeleton: Gas-Transport Properties and Molecular Dynamics Simulations

Abstract

A series of new semifluorinated polyimide (PI) films with phosphaphenanthrene skeleton were prepared by thermal imidization of poly(amic acid)s derived from a diamine monomer: 1,1-bis[2′-trifluoromethyl-4′-(4″-aminophenyl)phenoxy]-1-(6-oxido-6 H -dibenz⟨ c , e ⟩⟨1,2⟩oxaphosphorin-6-yl)ethane on reaction with four structurally different aromatic dianhydrides. The chemical structures of the polymers were established by Fourier transform infrared and 1 H NMR spectroscopy techniques. The polymers showed a good combination of thermal and mechanical properties ( T d10 up to 416 °C under synthetic air and tensile strength up to 91 MPa), low dielectric constant (2.10–2.55 at 1 MHz), and T g values as high as 261 °C. Gas permeabilities of these films were investigated for four different gases CO 2 , O 2 , N 2 , and CH 4 . The PI films showed high gas permeability ( P CO 2 up to 175 and P O 2 up to 64 barrer) with high permselectivity ( P CO 2 / P CH 4 up to 51 and P O 2 / P N 2 up to 7.1), and the values are better than those of many other similar polymers reported earlier. For the O 2 /N 2 gas pair, the PIs (PI A) surpassed the present upper boundary limit drawn by Robeson. A detailed molecular dynamics (MD) simulation study has been conducted to understand better the gas-transport properties. The effect of phosphaphenanthrene skeleton, its spatial arrangement, and size distribution function of the free volume were studied using molecular dynamics (MD) simulation and the results are correlated with the experimental data.

Synthesis of a furfural-based DOPO-containing co-curing agent for fire-safe epoxy resins

“…, phosphaphenanthrene and furan structure) in MBF-DOPO. 29–31 In summary, the small content of MBF-DOPO has little impact on the mechanical performance of the EP-0 network.…”

“…Meanwhile, the tensile and exural moduli of EP-4.0 are respectively increased by 6.2% and 8.3%, which is mainly a result of the more rigid structures (e.g., phosphaphenanthrene and furan structure) in MBF-DOPO. [29][30][31] In summary, the small content of MBF-DOPO has little impact on the mechanical performance of the EP-0 network.…”

Mechanistic Understanding of CO2 Adsorption and Diffusion in the Imidazole Ionic Liquid–Hexafluoroisopropylidene Polyimide Composite Membrane

“…The ion-pair lifetime method reported by previous authors is used to calculate the molecular pair lifetime, but all molecular types in the system are generalized. Therefore, it is possible to calculate the molecular pair lifetime of a neutral system and the ion-pair lifetime of a charged system . In 6FDA-ODA, the gas stays around the IL for a long time, and there is relatively little around the PI; in 6FDA-DPX and 6FDA-DAM with the methyl structure, the percentage of staying around PI is obviously higher than that of the IL.…”

Transport Properties of Thermoplastic R-BAPB Polyimide: Molecular Dynamics Simulations and Experiment

“…An analysis of the works, considering molecular dynamics simulations of polymer transport properties [25,26,27,28,29,30,31,32,33,34,35] indicates that the interactions of gas molecules with each other and with polymers may be described using two approaches. In most cases, parametrization of the interactions is based on the use of atomic types and the corresponding parameters already available in the force field [31,32,33,34,35]; however, some authors implement additional interaction parameters to the original force field, parameters which were developed specifically to describe the interactions between gas molecules [25,26,27,28,29,30].…”

“…A rigorous methodology developed in these works was proven to be an effective tool to address both practical and fundamental issues of polymer gas separation, such as establishing the mechanisms of gas mobility in polymers [26,27,30], calculating gas diffusion and solubility coefficients [26,28,29], and investigating swelling behavior of membranes [25]. Along with these studies, molecular dynamics simulations were also used to reveal correlations between the transport properties of polymers, their chemical structure, and the distribution of free volume in the membranes [33,34,35]. The results of these works showed that, by combining computer simulations and experimental studies, one can construct predictive models which may be used to formulate recommendations for developing new polymer materials with controlled properties.…”