Svetlana A. Prokhorova

Molecular imaging of monodendron jacketed linear polymers by scanning force microscopy

Polystyrene and polymethacrylate with 3,4,5-tris[4-(tetradecyloxy)benzyloxy]benzoic acid and 3,4,5-tris[3,4,5-tris(dodecyloxy)benzyloxy]benzyl alcohol side groups, respectively, were visualized by scanning force microscopy (SFM). The cylindrical molecules did not interpenetrate and their chain ends could be resolved in the images allowing quantitative evaluation of their length distribution. Whereas the polymethacrylate with the sterically most demanding side groups demonstrated a fairly good agreement between the SFM length and the calculated contour length, the polystyrene with the less branched substituent appeared to be at least two times shorter. The reduced length of the polymer chains was attributed to a disordered helixlike conformation.

Can polymer brushes induce motion of nano-objects?

In searching for new and efficient mechanisms for moving or propelling nano-sized objects across a flat surface, we discuss the idea of using the periodically switchable topography of a certain class of polymer substrates. In this paper, we exploit the peculiar properties of diblock-copolymer and mixed brushes that can undergo transitions between very distinct topographical patterns and a flat state. We investigate if, during the transition process, the reshaping of the surface structure, accompanied by a microphase transition, could deliver a sufficient amount of mechanical work to move objects adsorbed on the surface. We show this by following the spatial distribution of an ensemble of silica particles adsorbed on several kinds of poly(methyl methacrylate–b-glycidyl methacrylate) diblock-copolymer brushes, when the surface topography undergoes many periods of the switching process.