Abstract
Diblock copolymer thin films of polystyrene-block-poly(dimethyl siloxane) (PS-b-PDMS) featuring PDMS cylinders in a PS matrix are investigated during solvent vapor annealing with mixtures of n-heptane (which is strongly selective for PDMS) and toluene (which is close to nonselective for both blocks). Swelling in the vapor of one of the pure solvents and exchanging it stepwise by the vapor of the other solvent is compared to swelling in a given binary solvent vapor mixture for a prolonged time. The resulting structural changes, such as ordering of the cylinders on a hexagonal lattice and their transition into lamellae, are followed using in situ, real-time grazing-incidence small-angle X-ray scattering (GISAXS). In three runs, the sequence of solvent vapor swelling and vapor exchange is varied. Compiling the resulting morphologies in a diagram of states in dependence on the solvent content in the film and in the minority nanodomains allows insight into the role of the glass transition of the PS matrix for the ordering processes and their time scales. Based on these findings, a protocol is suggested to efficiently obtain an order-to-order transition from the cylindrical morphology with random domain orientation to the oriented lamellar state.
Highlights
Solvent Vapor Annealing of a Diblock Copolymer Thin Film with a Nonselective and a Selective Solvent: Importance of Pathway for the Morphological Changes
(PS-b-PDMS) featuring PDMS cylinders in a PS matrix are investigated during structures be prepared, and the nansolvent vapor annealing with mixtures of n-heptane and toluene
Swelling in the vapor of one of the pure solvents and exchanging it stepwise by the vapor of the other solvent is compared to swelling in a given binary solvent odomain orientation may vary and the detailed structure near the film interfaces may differ from the bulk structuring. [1,2,3,4] Nanostructured thin films have a variety of applications, e.g., as optical elements, vapor mixture for a prolonged time
Summary
Solvent Vapor Annealing of a Diblock Copolymer Thin Film with a Nonselective and a Selective Solvent Importance of Pathway for the Morphological Changes Jung, Florian; Berezkin, Anatoly V.; Tejsner , Tim Birger; Posselt, Dorthe; Smilgies, Detlef-M.; Papadakis, Christine M. Citation for published version (APA): Jung, F., Berezkin, A. B., Posselt, D., Smilgies, D-M., & Papadakis, C. Solvent Vapor Annealing of a Diblock Copolymer Thin Film with a Nonselective and a Selective Solvent: Importance of Pathway for the Morphological Changes.
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