A series of anion exchange membranes synthesised from poly (2, 6-dimethyl-1, 4-phenylene oxide) (PPO) have been investigated for water electrolysis applications. The prepared membranes were characterised using electrochemical impedance spectroscopy, infrared spectroscopy and thermal gravimetric analysis.Initial membranes showed very low ionic conductivity and poor stabilities (> 60 oC). Improvements to these membranes were sought by investigating the chloromethylation of PPO as well as chemical cross-linking. Cross-linking of the membranes produced a small increase in stability however these membranes remained unstable at temperatures above 70 oC. Increasing the chloromethylation reaction time to 6 hours proved to be the only way of increasing both ionic conductivity and stability, however membrane stabilities at 90 oC were still poor. Eventually a membrane stable at 90 oC for 1100 hours was prepared using a quaternised PPO and polysulphone (PS) blend.Reproducibility of the chloromethylated PPO (CMPPO) required to synthesise the membranes proved difficult. Thick polymer gels were observed which could not be used to make any membranes. A membrane was successfully prepared from a "semi gel" batch of CMPPO which showed the highest observed ionic conductivity (IC) whilst being stable at 90 oC. Improvements in stability without any loss of IC were achieved using secondary polymers as well as cross-linking agents. Investigation of a commercially available water soluble, poly(diallyldimethylammonium chloride) (polyDADMAC) proved to be ineffective due to the inability to render the materials insoluble in water. Selected membranes (based on ionic conductivity and stability) were tested for water electrolysis applications, with some of the membranes showing evolution of a small amount of oxygen and/or hydrogen.
|Date of Award||28 Sep 2017|
- University Of Strathclyde
|Supervisor||Vitor Magueijo (Supervisor) & Sudipta Roy (Supervisor)|