Beneficial use of hyperbranched polymer in cross‐linked anion exchange membranes for fuel cells

Abstract

Summary A series of cross‐linked blend membranes based on a linear poly(2,6‐dimethyl phenylene oxide) (PPO) and a hyperbranched poly(4‐vinylbenzyl chloride) (HVBC) are prepared via a simple solution casting procedure, followed by a cross‐linking treatment. The experiment indicates that the “HVBC enhancing PPO” membranes can have a looser cross‐linked “linear‐hyperbranched” blend structure, which is expected to improve the water absorption and dimensional stability. As a result, the excellent overall properties including high anion conductivity, low swelling, high strength, and excellent oxidative‐alkaline stability can be achieved simultaneously. A maximum conductivity of PPO‐HVBC‐100 (ion exchange capacity [IEC] ~ 1.88 mmol/g) is up to 135.9 mS/cm at 80°C, which is 2.9 times higher than that of pristine PPO membrane (IEC ~ 1.62 mmol/g). All the results reveal that the hyperbranched HVBC with a unique multi‐cation structure is a preferred “performance‐enhancing component” for the PPO‐based membranes, and this study also provides a novel idea for the preparation of high‐performance AEMs.

Study on AEMs with Excellent Comprehensive Performance Prepared by Covalently Cross-Linked p-Triphenyl with SEBS Remotely Grafted Piperidine Cations

“…5 Alternatively, the mechanical stability of AEMs can be improved by synthesizing more stable polymers and increasing their molecular weight. 6 Common polymer skeletons used in AEMs include poly-(vinyl alcohol)(PVA), 7,8 polyphenylene ether(PPO), 9,10 polyaromatic hydrocarbon skeleton, 11,12 poly(styrene-b-(ethyleneco-butylene)-b-styrene)(SEBS), 13 polyfluorene, 14 and perfluorinated polymers. 15 ammonium salts, 16,17 imidazolium cation, 18,19 cyclic cation, 20,21 quaternary phosphonium salt, 22 quaternium salt, 23 and guanidine salts.…”

“…Common polymer skeletons used in AEMs include poly­(vinyl alcohol)­(PVA), , polyphenylene ether­(PPO), , polyaromatic hydrocarbon skeleton, , poly­(styrene- b -(ethylene- co -butylene)- b -styrene)­(SEBS), polyfluorene, and perfluorinated polymers . Common cations include quaternary ammonium salts, , imidazolium cation, , cyclic cation, , quaternary phosphonium salt, quaternium salt, and guanidine salts .…”