Influence of dendrimer additives on the dewetting of thin polystyrene films

A small mass concentration of poly(benzyl ether) dendrimer added to a low molecular mass polystyrene is found to inhibit the dewetting of a thin (approximate to50 nm) polystyrene film from an acid-etched silicon substrate, The inhibition effect is found to depend on generation number where the lowest generation (G = 3) tested was the most effective. Our findings are qualitatively similar to previous observations by Barnes et al. [Macromolecules 2000,33,4177-4185.] where the addition of fullerenes ("buckyballs", C-60) similarly inhibited the dewetting of thin polystyrene and polybutadiene films. Thus, dewetting inhibition by nanoparticles appears to be a general effect, although certain conditions apparently need to be met for its occurrence. Specifically, a general tendency for the particles to segregate to the solid substrate seems to be required and the interaction between the particles and polymer must not be too unfavorable. The phase boundaries of the dendrimer-polymer mixtures depend on the generation, the higher generation being more miscible in terms of mass fraction. This suggests that the driving force for the dendrimer to segregate to the boundary is varied by changing the generation number, thus giving rise to a dendrimer generational effect on dewetting suppression.