Polyacrylamide crosslinked by bis-vinylimidazolium bromide for high elastic and stable hydrogels

A series of ionic compounds 1,n-dialkyl-3,3'-bis-l-vinylimidazolium bromide (C VIM) are prepared and employed to crosslink acrylamide for polyacrylamide (PAAM) hydrogel preparation via in situ solution polymerization. The swelling behavior, mechanical properties and thermal stability of the prepared C VIM crosslinked PAAM hydrogels are investigated. C VIM effectively crosslink the PAAM networks to form porous structures in the hydrogel, which could stably absorb water as much as 75.9 fold in weight without structural degradation. The prepared hydrogels could endure compressive stress up to 1.95 MPa and compressive deformation more than 90%. Meanwhile, the C VIM crosslinked networks show superior thermal stability, and could retain the structural integrity under 150 °C for more than 240 h. The swelling degradation resistance, mechanical strength and thermal stability of C VIM crosslinked hydrogels are much better than those of a conventional N,N'-methylenebisacrylamide crosslinked PAAM hydrogel. Using bis-vinylimidazolium bromides as crosslinkers provides an optional strategy for constructing thermally and mechanically robust hydrogel networks.