Abstract
Poly (γ-methyl L-glutamate) (PMLG) was mixed with one of the lipids, such as L-α-dilauroylphosphatidylcholine, L-α-distearoylphosphatidylcholine, egg yolk lecithin, trilaurin, cholesterol and cholesterylacetate, and spread at air-water interface as insoluble monolayers. The surface pressure-mean area curves were obtained. Three transitions were observed in the mixed monolayers. These were the collapse of lipid monolayer, the bilayer formation from polymer monolayer and the formation of duplex film. Neither the collapse pressures of the lipids nor the bilayer formation pressure of PMLG changed with compositions, indicating that PMLG and lipids were practically immiscible in the monolayers. The formation pressures of the duplex films mainly depended on the kind of polar groups of lipids. By considering the work of adhesion of the polymer to the polar groups of the lipids, it was concluded that PMLG molecules in the duplex films are situated under the lipid monolayers.
