Ionic liquid hydrogel templates: Bulkgel, cryogel, and microgel to be used for metal nanoparticle preparation and catalysis

Here, we report the preparation of various crosslinked polymeric matrices from 3-acrylami dopropyl)-trimethylammonium chloride as p(APTMACl) ionic liquid hydrogels in the forms of bulk gel, cryogel, and microgel. Their utilization for in situ metal nanoparticle synthesis of Co and Ni, and then the comparison of catalytic performances of these materials in the reduction of 4-nitrophenol (4-NP), 4-nitroaniline (4-NA), and 4-nitrobenzaldehyde (4-NBA) to the corresponding amine forms of 4-AP, 4-AA, and 4-ABA, respectively, are investigated. As the polymeric hydrogel matrices are inherently positively charged, the metal salts of CoCl2 and NiCl2 were loaded into hydrogel matrices from the corresponding metal salt solution in ethanol. It was found that morphology and sizes of p(APTMACl) ionic liquid hydrogel materials played a great role in catalytic performances for the nitro compounds. The effect of temperature and kinetic parameters of different polymeric matrices for the reduction of 4-NP to 4-AP was investigated. The activation energies for bulk gel, cryogel, and microgel were calculated as 44.74, 34.02, and 40.7 kJ mol-1, respectively. © 2015 Elsevier Ltd. All rights reserved