Adsorption of a novel fluorescent derivative of a poly(ethylene oxide)/poly(butylene oxide) block copolymer on octadecyl glass studied by total internal reflection fluorescence and interferometry

Abstract

We have used total internal reflection fluorescence (TIRF) to measure the adsorption kinetics of a newly synthesized fluorescent derivative of a triblock copolymer comprising two poly(ethylene oxide) arms connected by a poly(butylene oxide) segment. The composition is (EO)₄₀₀ (BO)₅₅ (EO)₄₀₀, in which EO represents ethylene oxide, BO represents butylene oxide, and one or both of the terminal OH groups of the two (EO)₄₀₀ arms are labeled with tetramethylrhodamine. The poly(butylene oxide) segment binds to hydrophobic octadecyl glass, used as a substratum. The TIRF signal is shown to be derived almost entirely from surface‐adsobed polymer. This facilitates calculation of adsorption isotherms from 0.1–0.005% bulk polymer solution by means of diffusion kinetics. Information about the effective thickness of the adsorbed polymer, determined by optical interference microscopy, corresponds with what is known about the conformation of similar molecules at interfaces and indicates monolayer adsorption on the glass. © 1994 John Wiley & Sons, Inc.