U.S. Department of Energy


Date of this Version



Published in Macromolecules 2006, 39, 8434-8439.


The kinetics of assembly of a series of poly(2-vinylpyridine)-polystyrene-poly(2-vinylpyridine) (PVP-b-PS-b-PVP) triblock copolymers from the selective solvent toluene onto a silicon surface has been studied using phase-modulated ellipsometry. The adsorbed amount and thickness have been determined independently as functions of time. Even though the adsorbed amount as a function of time follows the traditional two-step process that is typical of the self-assembly of diblock copolymerssthere is an initial fast adsorption followed by a slow buildup of the layer (brush regime) - the thickness shows an “overshoot” that corresponds to the brush regime. We attribute this phenomenon, not observed in the self-assembly of amphiphilic diblock copolymers, to having both ends of the chain tethered. The final ellipsometric thicknesses of the brush made from the triblocks are less than that expected for a single-end tethered brush made from a diblock copolymer with a buoy block of similar molecular weight. This result supports the conclusion that PVP-b-PS-b-PVP triblock copolymers adsorb mainly in a looplike conformation.