Swelling behavior of polyethylenimine–cobalt complex in water

Polyethylenimine (PEI) was cross-linked by polyepichlorohydrin (PECH) and the swelling behavior of cross-linked PEI–Co complex membranes in water was studied. The equilibrium swelling ratio of PEI–Co complex membranes is lower and the swelling rate is slower than that of cross-linked PEI membranes without cobalt ion complexation. Both the equilibrium swelling ratio and swelling rate of PEI–Co complex membranes increase with increasing the molar ratio of PEI to PECH. The equilibrium swelling ratio of PEI–Co complex membranes remains almost constant with the change of the membrane thickness or temperature. The diffusion mechanism of water through PEI–Co complex membranes was also discussed, and it is found that the diffusion of water primarily obeys Fickian’s law, and the activation energy of diffusion is calculated to be 40.4 kJ/mol.