Adsorption behavior of amphiphilic polymers: 1. Chromatographic and thermogravimetric characterization

The work reported here involves a study of the adsorption behavior of some amphiphilic polymers containing alternating copolymers of stearyl methacrylate, mono-n-octylitaconate, styrene, and 1-octadecene with maleic anhydride. We have employed chromatographic and thermogravimetric measurements in order to characterize the adsorption process. Silica gel was the stationary phase in the case of the polar column, and a mixture of THF/toluene or chloroform/toluene as the mobile phase. Toluene content in the mobile phase affects the capacity to desorb the polymer from the interface. The adsorption of the polymers onto silica substrates from toluene between other solvents has been measured also with static experiments. The results are discussed in terms of the incorporation of hydrophilic groups as maleic- anhydride or hydrophobic groups as stearyl and n-octyl chains. The solvent effect was also considered. Comparison of the adsorption isotherms for PA-18 onto hydrophilic substrate (Aerosil 200) from two different solvents shows strong competition of THF with the surface functionality of the substrate by the PA-18.