A New Pentiptycene‐Based Dianhydride and Its High‐Free‐Volume Polymer for Carbon Dioxide Removal

Abstract

In addition to possessing excellent chemical, mechanical, and thermal stability, polyimides and polyetherimides have excellent solubility in many solvents, which renders them suitable for membrane preparation. Two new monomers [a pentiptycene-based dianhydride (PPDAn) and a pentiptycene imide-containing diamine (PPImDA)] and a pentiptycene-based polyimide [PPImDA-4,4'-hexafluoroisopropylidene diphthalic anhydride (PPImDA-6FDA)] have been synthesized and characterized by FTIR and H NMR spectroscopy, gel-permeation chromatography, mass spectrometry, X-ray photoelectron spectroscopy, thermogravimetric analysis, differential scanning calorimetry, BET surface area, and X-ray diffraction. High-molecular-weight PPImDA-6FDA has remarkable thermal stability and excellent solubility in common organic solvents. It also has an extraordinarily high fractional free volume (0.233) owing to the presence of -C(CF ) - units, the rigid diamine, and the pentiptycene moiety in the polymer structure. It has high CO permeability (812 Barrer) owing to poor chain packing, which is caused by the fact that its rigid groups veil the influence of the ethereal oxygen groups in its backbone. It has the highest CO permeability among all reported pentiptycene-containing polymers (about six times higher than that of the most permeable one) without sacrificing selectivity. The high free volume, good microporosity, high solubility in many solvents, and remarkable thermal stability of PPImDA-6FDA point to the great potential of this polymer for CO removal.

Pentiptycene-Based Polyurethane with Enhanced Mechanical Properties and CO2-Plasticization Resistance for Thin Film Gas Separation Membranes

“…The creation of free volume is generally obtained by the disruption of chain packing in the polymer structure. Molecular modeling analysis and experimental studies suggest that adding bulky side groups or highly contorted structures effectively disrupt the chain packing and result in higher gas permeability. , Recently, new microporous polyimides with iptycene units have been designed to achieve fast and selective gas transport. , The polyimides with paddlelike triptycene moiety exhibit improved gas permeability compared to the traditional polyimides (e.g., Matrimid) . The enhancement is greater for pentiptycene-based polyimides with nearly 50% higher CO 2 permeability than that of the triptycene-based polyimide membrane .…”

“…Molecular modeling analysis and experimental studies suggest that adding bulky side groups or highly contorted structures effectively disrupt the chain packing and result in higher gas permeability. 5,6 Recently, new microporous polyimides with iptycene units have been designed to achieve fast and selective gas transport. 7,8 The polyimides with paddlelike triptycene moiety exhibit improved gas permeability compared to the traditional polyimides (e.g., Matrimid).…”

Polysulfone Membranes Incorporated with Reduced Graphene Oxide Nanoparticles for Enhanced Olefin/Paraffin Separation

“…These challenges have motivated the use of alternative technologies such as membrane separation, which is more energy‐efficient, easier to operate, and scalable . Polymers are highly of interest in developing gas separation membranes due to their facile synthesis, versatile properties, and relatively low costs . Commercial membranes made of polysulfone (PSF), cellulose acetate (CA), and matrimid‐5218 have demonstrated poor gas separation performance for olefins/paraffins .…”

Improved gas transport properties of polyurethane–urea membranes through incorporating a cadmium‐based metal organic framework

“…1,2 Among various types of membranes, selective polymeric membranes have shown to be the most promising. [3][4][5][6][7] However, the trade-off between permeability and selectivity, captured by Robeson upper bounds, 8 has restricted the application of these membranes. 9 Alloyed membranes [10][11][12] and mixed-matrix membranes (MMMs) [13][14][15][16] with improved morphology and physiochemical properties have allowed achieving separation performances closed to or above the upper bounds.…”

“…In recent years, membrane technology has received a lot of attention due to its high energy efficiency, high separation efficiency, low capital cost, compactness, and modularity . Among various types of membranes, selective polymeric membranes have shown to be the most promising . However, the trade‐off between permeability and selectivity, captured by Robeson upper bounds, has restricted the application of these membranes …”