Swelling behavior and network characterization of hydrogels from linear polyacrylamide crosslinked with glutaraldehyde

Polyacrylamide hydrogels have been prepared by crosslinking reaction between linear polyacrylamide (PAAm) and glutaraldehyde (GA) in acidic medium. The equilibrium swelling degree, modulus of elasticity and structure parameters of the network have been investigated as functions of the initial polymer concentration and the crosslinker content. Stability of GA crosslinks between PAAm chains has been demonstrated under the acid and basic conditions. It has been suggested that the crosslinking reaction can be presented as two stage process, which distinguishes different accessibility of aldehyde and amide groups for cross-linking agent in conditions of macromolecule distancing. The method provides formation of PAAm hydrogels with the values of the swelling degree and mechanical characteristics, which are close to the hydrogels prepared by traditional method of free radical crosslinking copolymerization.