Reversible absorbents for safe storage of toxic hydrazine were developed. Various cross-linked polar polymers were examined as absorbents for hydrazine and its 35% aqueous solution, and structurally similar polymers were found to be suitable for effective absorption. Namely, cross-linked polyacrylamide (CPAM) was most effective among examined various hydrophilic polymers. CPAM absorbed 43-and 31-fold heavier amounts of absolute hydrazine and 35% aqueous solution, respectively, by simple soaking. Absorbed hydrazine could be quantitatively released either by N 2 gas flow and compression, and the resulting absorbent reabsorbed hydrazine without loss of the absorption ability. The absorption ability was higher than conventional covalent storages, and the release protocol, without dissolution of the absorbent, are suitable for storage systems in hydrazine fuel cells.
A reversible gelation–release system was developed for safe storage of toxic hydrazine solution based on gelation at lower critical solution temperature (LCST). Poly(N-isopropylacrylamide) (PNIPAM) and its copolymer could form gels of 35wt% hydrazine by dissolution under low temperature and storage at ambient temperatures. For example, PNIPAM gelled a 63 fold heavier amount of 35wt% hydrazine. Aqueous hydrazine was released from the gels by compression or heating, and the gelation–release cycles proceeded quantitatively (> 95%). The high gelation ability and recyclability are suitable for rechargeable systems for safe storage of hydrazine fuels.
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