Early Stages of Film Creation in Thin Diblock Copolymer Films

Abstract

Thin poly(styrene-block-p-methylstyrene) diblock copolymer films on top of silicon substrates were examined right after preparation and during the early stages of annealing. Using specular and off-specular X-ray scattering as well as scanning force microscopy, the film morphology is determined. With the spin-coating technique films are prepared which exhibit a roughness correlation between the substrate and the copolymer surface within a limited film thickness and molecular weight range right after preparation. The transferred part of the roughness spectrum of the substrate is probed and explained as a morphology of a frozen liquid with a surface bending rigidity. During annealing the energetically unfavorable roughness replication decays, and an internal ordering is formed. The decay of long-range correlation is explained by a surface diffusion where diffusion is slowed down as compared to bulk behavior.

Grazing incidence small-angle X-ray scattering: an advanced scattering technique for the investigation of nanostructured polymer films

“…In addition the detector scan shows the presence of interface correlation between the substrate and the diblock copolymer surface. The presence of correlated roughness was reported in diblock copolymer films only in systems with a smaller immiscibility between both blocks, like in poly(styreneblock-para-methylstyrene) [45]. Since this feature is present in homopolymer [42,43], polymer blend [46], and diblock copolymer films [45], this opens the question whether spin coating always installs correlated interfaces, irrespective of the type of polymer used.…”

“…A value of R c =293 nm is determined. Therefore the cut-off introduced after spin coating, is larger than the typical molecular lengths, like the bulk lamellar spacing [45].…”

Morphology of Lithium‐Containing Diblock Copolymer Thin Films

“…Because we obtained homogeneous but not nanostructured Li salt‐containing DBC films in the range of added Li salt amount (weight ratio) of 0.15 > Li/PEO > 0.035, we applied a post‐production treatment to these thin hybrid films. Typically, the solvent annealing of BC films is a well‐known post‐treatment method to produce highly ordered, nanostructured polymer films 9, 44, 77–80. In this study, a water‐benzene mixed solvent vapor was used instead of pure solvent vapor because of the inevitable dewetting behavior of the polymer films in pure benzene vapor.…”

Phase Transition and Phase Transformation in Block Copolymer Nanoparticles

“…To transform them to equilibrium structures and control their orientation, many different techniques have been reported 5–10. Conventionally, block copolymer films are annealed for long periods (e.g., two days to several weeks) at a temperature higher than the glass transition temperature ( T g ) but lower than the order–disorder transition temperature ( T ODT ) of block copolymers 11–14. Cavicchi and Russell15 have developed a facile technique of forming uniform phase separation structures by exposing a block copolymer film to vapor of its good solvent instead of thermal annealing.…”