Lamellae Orientation in Block Copolymer Films with Ionic Complexes
Lamellae orientation in lithium-complexed polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) copolymer films on natively oxidized silicon wafers is investigated as a function of film thickness and percentage of carbonyl groups coordinated with lithium ions using cross-sectional transmission electron microscopy and grazing incidence small-angle X-ray scattering. For films with a lower percentage of ionic complexes, the strong surface interaction of the PMMA blocks with the substrate is not changed significantly and the orientation of the lamellar microdomains depends on the film thickness and is dictated by a coupling of the interfacial interactions and the degree of microphase separation. For films with a higher percentage of ionic complexes, the surface interaction is mediated. Along with the enhanced immiscibility between the two blocks, which drives the self-assembly into a stronger microphase segregation, an orientation of the lamellar microdomains normal to the surface is seen, independent of film thickness. Thus, by tuning the amount of ionic complexes, the orientation of lamellar microdomain can be controlled from a random arrangement to being oriented parallel or perpendicular to the film surface without any surface modification or use of external fields, which opens a simple and general route for the fabrication of nanostructured materials.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 959545
- Report Number(s):
- BNL-82531-2009-JA; LANGD5; TRN: US1005755
- Journal Information:
- Langmuir, Vol. 24, Issue 7; ISSN 0743-7463
- Country of Publication:
- United States
- Language:
- English
Similar Records
“Structurally Neutral” Densely Packed Homopolymer-Adsorbed Chains for Directed Self-Assembly of Block Copolymer Thin Films
Combinatorial Block Copolymer Ordering on Tunable Rough