Wetting kinetics of modified polyimide surfaces: interactions with polar solvents

Contact angle relaxation studies were performed on a base hydrolyzed PMDA-ODA polyimide surface using methanol, pyridine and 1-methyl-2-pyrrolidinone (NMP) as probe liquids. The results were fitted parametrically to the molecular-kinetic theory to obtain the relevant molecular parameters that govern wetting rates. The probe liquid NMP appeared to have the greatest interaction of the three solvents studied with the modified polyimide surface. The differences in wetting rates are explained to result from the hydrogen bonding capability of the probe liquids with the modified polyimide surface and due to the difference between bulk and surface pKa of the modified polyimide.