Bending elasticity of a curved amphiphilic film decorated with anchored copolymers: a small angle neutron scattering study

Microemulsion droplets (oil in water stabilized by a surfactant film) are progressively decorated with increasing amounts of poly( ethylene oxide) (PEO) chains anchored in the film by the short aliphatic chain grafted at one end of the PEO chain. The evolution of the bending elasticity of the surfactant film with increasing decoration is deduced from the evolution in size and polydispersity of the droplets as reflected by small angle neutron scattering. The optimum curvature radius decreases while the bending rigidity modulus remains practically constant. The experimental results compare well with the predictions of a model developed for the bending properties of a curved film decorated with nonadsorbing polymer chains, which takes into account the finite curvature of the film and the free diffusion of the chains on the film.