Adsorption and wetting properties of pluronic block copolymers on hydrophobic surfaces studied by optical waveguide lightmode spectroscopy and dynamic tensiometric method

Adsorption of four different poly(ethylene oxide)/poly(propylene oxide)/poly(ethylene oxide) triblock copolymers (Pluronics) onto the hydrophobized surface of the sensor was measured by the optical waveguide lightmode spectroscopy (OWLS). Adsorbed amounts of Pluronic PE10300, PE10500, PE6400, and PE6800 determined in the concentration range of 10-2-10 gdm-3 were found to follow the order of the hydrophobicity of the Pluronic compounds characterized by their hydrophil-lipophil balance (HLB) values. Wettability of two hydrophobic surfaces, the poly(lactide-co-glycolide), PLGA70/30 copolymer (used as drug carrier in pharmaceutical applications) and silylated glass, in aqueous solutions of the above Pluronics were studied by a dynamic tensiometric method. The significant increase in the wetting tension observed after the adsorption of the surfactants, and hence the decrease of the apparent contact angle as the indication of the wetting effect on both the biopolymer and the hydrophobic glass, was correlated to the poly(ethylene oxide) (PEO) content of the adsorbed layer obtained on the hydrophobized sensor surface by the OWLS method.