Cross-Linked Polyphosphazene Blends as Robust CO₂ Separation Membranes

Abstract

An effective cross-linking technique allows a viscous and highly gas-permeable hydrophilic polyphosphazene to be cast as solid membrane films. By judicious blending with other polyphosphazenes to improve the mechanical properties, a membrane exhibiting the highest CO2 permeability (610 barrer) among polyphosphazenes combined with a good CO2/N2 selectivity (35) was synthesized and described here. The material demonstrates performance stability after 500 h of exposure to a coal-fired power plant flue gas, making it attractive for use in carbon capture applications. Its CO2/N2 selectivity under conditions up to full humidity is also stable, and although the gas permeability does decline, the performance is fully recovered upon drying. The high molecular weight of these heteropolymers also allows them to be cast as a thin selective layer on an asymmetric porous membrane, yielding a CO2 permeance of 1200 GPU and a CO2/N2 pure gas selectivity of 31, which does not decline over 2000 h. In addition to gas separation membranes, this cross-linked polyphosphazene can potentially be extended to other applications, such as drug delivery or proton exchange membranes, which take advantage of the polyphosphazene’s versatile chemistry.

Carbon Capture Membranes Based on Amorphous Polyether Nanofilms Enabled by Thickness Confinement and Interfacial Engineering

“…Polyethers exhibit excellent CO 2 /N 2 separation properties because of the affinity of polar ether oxygens toward CO 2 (generating high CO 2 /N 2 solubility selectivity) and excellent chain flexibility (inducing high CO 2 diffusivity). ,− For example, amorphous cross-linked poly­(ethylene oxide) (XLPEO) were synthesized from 80 mass % polyethylene glycol methyl ether acrylate (PEGMEA) and 20 mass % polyethylene glycol diacrylate (PEGDA) and exhibited CO 2 permeability of 600 Barrer [1 Barrer = 10 –10 cm 3 (STP) cm cm –2 s –1 cmHg –1 ] and CO 2 /N 2 selectivity of 51 at 35 °C . Furthermore, XLPEO can be blended with plasticizers to improve CO 2 permeability. − For example, incorporation of 60 mass% 18-crown-6 (C6) into XLPEO increased CO 2 permeability by 120% to 1340 Barrer while retaining CO 2 /N 2 selectivity of ≈48.…”

Preparation of Magnetically Recoverable MPCTP-Ag Composite Nanoparticles and Their Application as High-Performance Catalysts

“…Because of their characteristics of organic–inorganic hybrid, polyphosphazene with different functions can be synthesized by molecular design to meet different application requirements. It has been widely used in the fields of flame retardants, elastomers, drug delivery, , membranes, supercapacitors, , etc. However, there are few reports about polyphosphazene-based recyclable nanocatalysts.…”

Mixed substituent ether‐containing polyphosphazene/poly(bis‐phenoxyphosphazene) blends as membranes for CO2 separation from N2

“…Further, the 30 psi (2 Bar) pressure applied during the pure gas measurements hastened creep and flow. Historically, cross‐linking in these polymers has been accomplished using several methods including chemical, 14,24 and UV, 25,26 gamma, 27,28 and electron beam irradiation 17 …”