Morphological Evolution of Poly(solketal methacrylate)-block-polystyrene in Thin Films

The morphological evolution of the lamellar microdomains for the thin films of symmetric poly(solketal methacrylate-b-styrene) (PSM-b-PS) copolymers that can be converted into poly(glycerol mono-methacrylate-b-styrene) (PGM-b-PS) copolymers by the hydrolysis reaction was investigated. This simple hydrolysis was performed in the solid state using an acid vapor and markedly improves the segmental interaction parameter (χ) from 0.035 to 0.438 at 25 °C. For the perpendicular orientation of the lamellar microdomains, the hydroxyl-terminated random copolymer (PSM-r-PS) with f_PSM = 0.5 was used to tune the interfacial interactions at the substrate as a neutral and it can also be transformed into PGM-r-PS with the block copolymers. Scanning force microscope (SFM) and grazing-incidence small angle X-ray scattering (GISAXS) measurements as a function of the exposure time to an acid vapor were conducted to characterize the transition from the disorder to order state as well as the perpendicular orientation and features of the lamellar microdomains. As a result, sub-10 nm full pitch lamellar patterns in the thin films were achieved after full conversion and thermal annealing.