Hydrophilic isopropanol/acetone-substituted polymers for safe hydrogen storage

The development of hydrogen carriers that are free from safety risks such as explosivity, volatility and toxicity is essential for safe hydrogen storage. In this study, we synthesize a safe and hydrophilic isopropanol/acetone-substituted polymeric hydrogen carrier by a facile synthetic procedure that is conducted in water and only requires dialysis with water for purification. A simple nucleophilic substitution of poly(allylamine) and 2-bromoacetone produces a hydrophilic acetone-substituted poly(allylamine) derivative, facilitating control over the hydrophilicity of the polymer according to the degree of substitution. The polymer is readily hydrogenated using NaBH₄ to obtain a hydrophilic isopropanol-substituted poly(allylamine). The high density of the repeating units and high hydrophilicity of the amine groups enable the maximization of the mass hydrogen storage density of the redox polymer to ca 1.5 wt%. Reversible hydrogen gas fixation/release from the polymeric hydrogels via chemical bond formation/disconnection is realized with complete conversion, with dehydrogenation occurring at 65–95 °C in the presence of an iridium complex catalyst.