Interactions between maleic acids copolymers and metal ions at the air-water interface and in the LB films

Abstract

Interactions between polymers of different backbones and metal ions at the air-water interface and the transfer of the metal ions into the LB films were investigated. The polymers containing side chains of carboxyls, hydrocarbon tails, and/or oligoethers were obtained from a precursor copolymer which was synthesized from a radical copolymerization of maleic anhydride and n-octadecyl vinyl ether. The metal ions examined were Na +, Mg 2+, and A1 3+. The surface pressure-area isotherms showed that the monolayers on aqueous metal ions have more expanded phases than on pure water in sequence of Al 3+ > Mg 2+ > Na +. From the Fourier transform infrared spectra, the formation of carboxylate salts and the orientation of backbone and pendant chains of the copolymers in the Langmuir-Blodgett (LB) films were estimated. Quantitative analysis of the metal ions transferred into the LB film was carried out by X-ray photoelectron spectroscopy measurement. The Mg 2+ ion was the most abundant in the LB films, and two repeat units of the copolymers corresponded to about one Mg 2+ ion. The concentration of metal ions in the LB films was in the order Mg 2+ > Al 3+ > Na +, however, the difference in concentration according to the backbone structures was small.