Adsorption of Polyethylene from Solution onto Starch Film Surfaces

We prepared starch films by jet-cooking aqueous dispersions of high-amylose starch and then allowing the jet-cooked dispersions to air-dry on Teflon surfaces. When the starch films were immersed in 1% solutions of polyethylene (PE) in 1-dodecanol, dodecane, and xylene at 120 degrees C and the solutions were allowed to slowly cool, PE precipitated from the solutions and adsorbed onto the starch film surfaces. Fourier transform infrared spectroscopy was used to estimate the micrograms of PE adsorbed per square centimeter of starch film. PE was preferentially adsorbed onto the film side that was in contact with the Teflon surface during drying. The amount of PE adsorbed ranged from about 8 to 45 mu g/cm(2) and depended upon the solvent used and the final temperature of the cooled solution. Scanning electron microscopy of the starch film surfaces showed discontinuous networks of adsorbed PE on the Teflon side and widely spaced nodules of adsorbed PE on the air side. NMR analysis showed that the PE adsorbed onto the starch surface was more linear and/or had a higher molecular weight than the starting PE. Possible reasons for the selective adsorption of PE onto the Teflon side of the starch film surface are discussed. (C) 2009 Wiley Periodicals, Inc.(dagger) J Appl Polym Sci 114: 1840-1847, 2009