SAXS study of the lamellar-cylindrical transition in the PI-b-P2VP(OG) supramolecules' system

A detailed SAXS study of self-assembled block copolymer-based supramolecules composed of a polyisoprene-block-poly(2-vinylpyridine) diblock copolymer and octyl gallate that is hydrogen bonded to the vinylpyridine block in a stoichiometric ratio is presented. The changes in the system morphology with temperature are investigated both at rest and under oscillatory shear. In between the lamellar-to-cylindrical transition a new intermediate structure, identified as a deformed hexagonal structure (DHS), was observed. Being at rest the DHS is argued to consist of ellipsoidal cylinders that adopt a more regular circular shape when the sample is subjected to shear. These results are discussed in terms of hydrogen bond breaking under shear.