Reptation in langmuir polymer monolayers

We report the existence of reptation motion typical of entangled polymer chains in dense polymer monolayers spread at the air-water interface. Ellipsometry determinations of the layer thickness reveal a thickening of the layers in the semi-dilute region, enabling the existence of entanglements. Relaxation measurements were performed using compression and shear surface deformations. The resulting dependence on the chain concentration and size are compatible with the existence of diffusion reptation motions controlling molecular transport inside the monolayer. As in the bulk, these features are observed above a critical number of monomers, N-e, for which chain entanglements become possible.