PEG polymer brushes via the Langmuir-Schaefer technique: The transfer ratio

The Langmuir-Schaefer technique allows horizontal transfer of monolayer films of amphiphilic molecules from an air-water interface to a hydrophobic solid substrate. Spectroscopic ellipsometry has been used to estimate the transfer ratio of Polyethylene Glycol (PEG) polymer brushes prepared by this Langmuir-Schaefer method. We measured the transfer ratio for various degrees of polymerization and surface densities at the air-water interface. We do not observe a significant change of transfer ratio with the degree of polymerization. We also show that the transfer ratio is lower from an air-water monolayer film in the liquid phase than from a monolayer in the solid phase. Control over the transfer ratio is a crucial step in many experiments since the efficacy of the repression of proteins depends strongly on the assumption of the characteristics of the brushes. (C) 2012 Elsevier Inc. All rights reserved.