Synthesis and Gas-Permeation Characterization of a Novel High-Surface Area Polyamide Derived from 1,3,6,8-Tetramethyl-2,7-diaminotriptycene: Towards Polyamides of Intrinsic Microporosity (PIM-PAs).

Giuseppe Genduso,Yingge Wang,Ingo Pinnau,Bader Ghanem

doi:10.3390/polym11020361

Giuseppe Genduso, Yingge Wang + Show 2 more

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https://doi.org/10.3390/polym11020361

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Journal: Polymers	Publication Date: Feb 19, 2019
Citations: 22	License type: CC BY 4.0

Affiliation: King Abdullah University of Science and Technology

Abstract

A triptycene-based diamine, 1,3,6,8-tetramethyl-2,7-diamino-triptycene (TMDAT), was used for the synthesis of a novel solution-processable polyamide obtained via polycondensation reaction with 4,4′-(hexafluoroisopropylidene)bis(benzoic acid) (6FBBA). Molecular simulations confirmed that the tetrasubstitution with ortho-methyl groups in the triptycene building block reduced rotations around the C–N bond of the amide group leading to enhanced fractional free volume. Based on N2 sorption at 77 K, 6FBBA-TMDAT revealed microporosity with a Brunauer–Emmett–Teller (BET) surface area of 396 m2 g−1; to date, this is the highest value reported for a linear polyamide. The aged 6FBBA-TMDAT sample showed moderate pure-gas permeabilities (e.g., 198 barrer for H2, ~109 for CO2, and ~25 for O2) and permselectivities (e.g., αH2/CH4 of ~50) that position this polyamide close to the 2008 H2/CH4 and H2/N2 upper bounds. CO2–CH4 mixed-gas permeability experiments at 35 °C demonstrated poor plasticization resistance; mixed-gas permselectivity negatively deviated from the pure-gas values likely, due to the enhancement of CH4 diffusion induced by mixing effects.

Highlights

Polyamides are synthetic macromolecules containing amide groups (–CO–NH–) mainly prepared via polycondensation reaction between diamines and diacid-type monomers
Aromatic and semi-aromatic polyamides have been broadly applied in the industry, due to their extraordinary mechanical, chemical, and thermal properties [1]
Aromatic polyamides (“aramids”) are in use for the production of synthetic fibers of superior mechanical strength and heat resistance (e.g., Kevlar and Nomex fibers). Another important application of aromatic polyamides is the production of thin-film composite membranes by interfacial polymerization [2] for water desalination via reverse osmosis (RO); the employment of these membranes revolutionized desalination industry by making RO more cost efficient than conventional energy-intensive thermal processes [3]

Summary

Introduction

Polyamides are synthetic macromolecules containing amide groups (–CO–NH–) mainly prepared via polycondensation reaction between diamines and diacid-type monomers. Aromatic and semi-aromatic polyamides have been broadly applied in the industry, due to their extraordinary mechanical, chemical, and thermal properties [1]. Aromatic polyamides (“aramids”) are in use for the production of synthetic fibers of superior mechanical strength and heat resistance (e.g., Kevlar and Nomex fibers). Another important application of aromatic polyamides is the production of thin-film composite membranes by interfacial polymerization [2] for water desalination via reverse osmosis (RO); the employment of these membranes revolutionized desalination industry by making RO more cost efficient than conventional energy-intensive thermal processes [3]. For gas adsorption and gas storage applications, aromatic network polyamides are Polymers 2019, 11, 361; doi:10.3390/polym11020361 www.mdpi.com/journal/polymers

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