Adsorption of pluronic F-127 on surfaces with different hydrophobicities probed by quartz crystal microbalance with dissipation.

Triblock copolymers of polyethylene oxide (PEO) and polypropylene oxide (PPO), that is, PEOn-PPOm-PEOn, better known as Pluronic can adsorb to surfaces in either a pancake or a brushlike configuration. The brushlike configuration is advantageous in numerous applications, since it constitutes a surface repellent to proteins and microorganisms. The conformation of the adsorbed Pluronic layer depends on the hydrophobicity of the substratum surface, but the hydrophobicity threshold above which a brushlike conformation is adopted is unknown. Therefore, the aim of this study is to investigate Pluronic F-127 adsorption on surfaces with different hydrophobicities using a quartz crystal microbalance with dissipation. Adsorption in a brushlike conformation occurred on surfaces with a water contact angle above 80 degrees , as inferred from the thickness, viscosity, and elasticity of the adsorbed layer. The concentration of Pluronic F-127 in solution affected only the kinetics of adsorption and not the final layer thickness or conformation of adsorbed Pluronic molecules.