Nanoscopic surface patterns from functional ABC triblock copolymers

We synthesized analogous series of monodisperse ABC triblock copolymers wit h symmetrical end blocks A/C and different short middle blocks B (5-10 wt % ) with varying polarities by sequential anionic polymerization, i.e., polys tyrene-b-poly(2-vinylpyridine)-b-poly(methyl methaerylate) (PS-b-P2VPb-PMMA ) and polystyrene-b-poly(2-hydroxyethyl methaerylate)-b-poly(methyl methacr ylate) (PS-b-PHEMA-b-PMMA). Thin (thickness similar to 20 nm) and ultrathin films (thickness less than or equal to 7 nm) were prepared by either dip-c oating or adsorption from solution onto silicon wafers. The copolymer films were investigated by scanning force microscopy. In thin films, the polar m iddle block adsorbs preferentially to the polar substrate, resulting in a p olymer film surface that exclusively consists of PS and PMMA microdomains. In ultrathin films, the two polar B and C blocks behave like a single B blo ck resulting in structures which can be described by recent scaling laws. T he lateral spacing and the morphology of the structures can be controlled b y film thickness and A/C block length.