Inverted Cylindrical Microdomains from Binary Block Copolymer Blends Capable of Hydrogen Bonding

Abstract

A binary blend of polystyrene-block-poly(2-vinyl-pyridine) copolymer (PS-b-P2VP) and polystyrene-block-poly(4-hydroxystyrene) copolymer (PS-b-PHS) was studied to obtain an inverted cylindrical morphology with cylinders consisting of the major block. Both neat block copolymers with slightly asymmetric volume fraction of the PS block (f(PS) similar to 0.65) showed lamellar microdomains. The blends showed phase transformation from lamellae to inverted cylinders because of hydrogen bonding between nitrogen in P2VP and hydroxyl group in PHS chains. The formation of the inverted cylinders depends on f(PS) in the blend and the molecular weight ratio (r) of PS-b-P2VP to PS-b-PHS because both parameters affect the interfacial curvature arising from the hydrogen bonding and chain stretching near the interface.