Adhesive Interaction in Water between Surfaces with Various Zeta Potentials

Abstract

To obtain polymer surfaces having different zeta potentials, a poly(ethylene terephthalate) (PET) film surface was graft-polymerized with an anionic monomer, acrylic acid (AAc), and a cationic monomer, N,N-dimethylaminoethyl methacrylate (DMAEMA). In addition, a cellulose film was surface-modified with chloroacetic acid to introduce anionic carboxyl groups and N,N-dimethylaminopropyl acrylamide (DMAPAA) to introduce cationic dimethylamino groups. Through these surface modifications we could obtain films having zeta potentials ranging from +39 to −58 mV. Adhesive interaction in water between two surfaces of these films was measured with a tensile testing method after lapping the two surfaces in water. When one film was surface-grafted with cationic polymer chains, it exhibited significant adhesion instantaneously in water toward the other surface with a negative zeta potential, such as the surface-modified cellulose films, quartz, and the unmodified PET film. The quartz surface showed a detectable attractive force toward the cationic cellulose surface, but the force was weaker than that toward the cationically grafted surface. Apparently, no correlation was found between the zeta potential of the surfaces and their adhesive strength.