2LL-2 : Realizing Sub-10 nm Nanostructures Using Responsive Block Copolymers by a Solid-State Transformation

In this study, a high χ-low N system was developed for a self- assembled BCP morphology with a sub-10 nm period through an acid-catalyzed hydrolysis of symmetric poly(solketal methacrylate-b-styrene) (PSM-b-PS) copolymers. The acid-catalyzed hydrolysis transforms PSM-b- PS, having two hydrophobic blocks, into poly(glycerol monomethacrylate- b-styrene) (PGM-b-PS), having one hydrophilic and one hydrophobic block. This simple transformation significantly enhances χ such that a phase-mixed PSM-b-PS can be transformed in the solid-state into a microphase separated BCP without the use of any additives. Small-angle X-ray scattering (SAXS) measurements as functions of the degree of polymerization and PSM conversion were performed to examine the lamellar microdomain features. With the large increase in χ, even smallest synthesized PGM-b-PS copolymers underwent microphase separation, allowing us to achieve a center-to-center lamellar microdomain spacing of 5.4 nm.