Bulk Properties of a Cyanogel Network: Toward an Understanding of the Elastic, Mechanical, and Physical Processes Associated with Sol-Gel Processing of Cyanide-Bridged Gel Systems

The reaction of aqueous solutions of Na₂PdCl₄ and K₃Co(CN)₆ results in gelatinous polymeric materials, characterized by bridging cyanides between the central metals of the adducts. Such materials are referred to as cyanogels. A mechanical perturbation method, three-point beam-bending, was used to measure the viscoelastic relaxation behavior and permeability of a series of Pd/Co cyanogels of differing concentrations. The shear and Young's modulîi of the cyanogel network was found to increase with an increase in concentration. Permeability was found to decrease with an increase in concentration, and was found to range from 239 to 3.67 nm² over the concentration range 0.175-0.600 M. This suggests that the Pd/Co cyanogel contains an average pore structure size with the radii ranging from 40 to 5 nm over the concentration range investigated.