Monolayers of Diblock Copolymer Micelles by Spin-Coating from o-Xylene on SiOx/Si Studied in Real and Reciprocal Space
journal contributionposted on 28.02.2012, 00:00 by Jiun-You Liou, Ya-Sen Sun
Polystyrene-block-poly(2-vinylpyridine), P(S-b-2VP), micelles of nanometer size and core–shell spherical shape were deposited as monolayers on silicon substrates (SiOx/Si) with varied surface coverage using spin coating from polymer solutions in o-xylene of varied polymer concentration. Simply on varying the polymer solution, the micellar surface coverage on SiOx/Si, spatial order, and organization of micelles were tailored in the monolayer regime. The surface morphology of P(S-b-2VP) micelles was explored with grazing-incidence small-angle X-ray scattering (GISAXS) and an atomic force microscope (AFM). Quantitative analysis and simulations of the X-ray scattering pattern were performed to derive the dependence of the structural and ordering parameters of micelles on the P(S-b-2VP) concentration. Four spatial arrangements were investigated. Upon progressively increased surface coverage with increasing concentration, disordered spherical micelles, loosely packed spherical micelles with hexagonal order, ordered spherical micelles with random loosely packed densities, and closely packed spherical micelles with short-range order were obtained sequentially. This system thus serves as a model for analysis of the impact of surface coverage as a function of polymer concentration on the shape, size, size distribution, and assembly of truncated micelles within two-dimensional monolayers on SiOx/Si.