Adsorption mechanisms of charged, amphiphilic diblock copolymers: The role of micellization and surface affinity

We have studied the adsorption of charged, amphiphilic diblock copolymers above the critical micelle concentration to develop a systematic understanding of the effects of micellization on the adsorption kinetics. Two distinct regimes are found. If the micelle-surface interaction is sufficiently weak, micelles do not adsorb and the adsorption kinetics depends only on the critical micelle concentration, that is, on the concentration of free chains in solution. When the micelle-surface interaction is attractive, micelles directly adsorb; however, the initial adsorption rate is slower than that predicted from diffusion rates alone. It is suggested that micelles must overcome a potential barrier to adsorb, the rate determined by a balance between the compressibility of the corona and the strength of the micelle-surface interaction.