MONOLAYER MISCIBILITY OF A HAIRY RODLIKE POLYGLUTAMATE AND N-ALKYL AMPHIPHILES

Surface pressure-area (pi-A) isotherms have been measured for mixtures Of l-L-glutamate)-co-(gamma-n-octadecyl-L-glutamate)} (methyl/octadec yl = 7/3) with a series of normal chain amphiphiles (C16-, C18-, and C 20-fatty acids and ethyl stearate). Excess areas and two-dimensional c ompressibilities were determined from the pi-A isotherms. The deviatio ns from ideality when these values are plotted against composition wer e interpreted on the basis of a two-phase model with the phases varyin g in composition depending on the amphiphile-amphiphile interaction. I n the case of ethyl stearate a mixed phase is observed above a certain surface pressure, which corresponds to the phase transition of a pure ethyl stearate monolayer from the liquid condensed phase L2 to the su perliquid phase LS. Complementary experimental evidence for the propos ed model is given by fluorescence energy transfer experiments on trans ferred monofilms where the polymer component ig substituted by a mixtu re of a carbazole and anthracene tagged polymer, respectively. FTIR st udies on polymer/amphiphile mixtures in which the polymer has perdeute rated side chains show that the polymer side chains become aligned mor e perpendicular to the substrate as a result of mixing with ethyl stea rate.