Concurrent Transformation of Copolymer Domain Morphology Induced by the Order−Disorder Transition of Comb Block in Supramolecular Comb−Coil Block Copolymer

Abstract

An amphiphilic surfactant, dodecylbenzenesulfonic acid (DBSA), was complexed with poly(ethylene oxide) (PEO) block in poly(1,4-butadiene)-block-PEO (PB-b-PEO) through hydrogen bonding to yield a molecular architecture resembling comb−coil diblock copolymer. For the two binding fractions (x = 0.5 and 1.0 with x being the average number of DBSA molecules bound with one PEO monomer unit) studied, the supramolecular comb−coil diblocks exhibited a cylinder-within-lamellae morphology, where the PB cylindrical domains of ca. 28 nm in diameter embedded in the matrix consisting of the lamellar mesophase with the interlamellar distance of ca. 2.9 nm organized by the PEO(DBSA)x comb blocks. The interdomain distance of PB cylinders was significantly smaller than the fully extended length of the PEO block, indicating that the PEO chains confined within the polar layers in the lamellar mesophase were not fully stretched normal to the interface of PB microdomain; alternatively, they adopted a folded conformation while l...