Abstract
We present results of direct measurements of polymer depletion layers at the liquid/air interface using neutron reflectivity. The systems studied are semidilute solutions of polystyrene in toluene using polymers of different molecular weights. The thickness of the depletion layer d is found to be of the order of the correlation length ξ of the polymer in the bulk solution. We show, for the first time, the existence of a depletion layer at the free surface of a polymer solution when >, where and are surface tensions of pure polymer and pure solvent, respectively. We show also that the thickness of the depletion layer scales with the bulk concentration as d∼.
- Received 17 December 1990
DOI:https://doi.org/10.1103/PhysRevLett.67.2838
©1991 American Physical Society