LAUSR

Copolymer composed of two poly(2-vinylpyridine) blocks and one polystyrene block ((P2VP)2–PS) with a PS volume fraction (ΦPS) of 0.44 was synthesized, and their morphologies in bulk and thin films were compared to linear block copolymers (BCPs) having a similar ΦPS (PS-b-P2VP). For the symmetric diblock copolymer, a lamellar morphology was observed after thermal annealing, as was expected. However, (P2VP)2–PS in the bulk showed a hexagonally packed cylindrical microdomain morphology with PS forming the cylindrical microdomains in a P2VP matrix. In thin films, after solvent annealing in the vapors of a chloroform/ethanol mixture, the cylindrical microdomain morphology was retained and the microdomains were oriented parallel to the substrate surface. With the addition of ethanol into the annealing solvent, the morphology of (P2VP)2–PS was transformed from a bicontinuous morphology to one with cylindrical microdomains of PS oriented parallel to the substrate. The lamellar microdomain of the PS-b-P2VP copolym...