Directed Copolymer Assembly on Chemical Substrate Patterns: A Phenomenological and Single-Chain-in-Mean-Field Simulations Study of the Influence of Roughness in the Substrate Pattern
- 8 December 2007
- journal article
- Published by American Chemical Society (ACS) in Langmuir
- Vol. 24 (4), 1284-1295
- https://doi.org/10.1021/la702482z
Abstract
The directed assembly of lamella-forming copolymer systems on substrates chemically patterned with rough stripes has been studied using a Helfrich-type, phenomenological theory and Single-Chain-in-Mean-Field (SCMF) simulations.The stripe period matches that of the lamellar spacing in the bulk. The effect of the line edge roughness (LER) of the substrate pattern on the microphase-separated morphology was investigated considering two generic types of substrate LER with a single characteristic wavelength imposed on the edges of the stripes: undulation and peristaltic LER. In both cases, the domain interfaces are pinned to the rough stripe boundary at the substrate and, thus, are deformed. We study how this deformation decays as a function of the distance from the substrate. The simple theory and the SCMF simulations demonstrate that one of the basic factors determining the decay of the roughness transferred into the self-assembled morphology is the characteristic LER wavelength of the substrate pattern; i.e., the distance over which the roughness propagates away from the substrate increases with wavelength. However, both approaches reveal that, for a quantitative understanding of the consequences of substrate LER, it is important to consider the interplay of the pattern wavelength with the other characteristic length scales of the system, such as the film thickness and the bulk lamellar spacing. For instance, in thin films, the induced deformation of the lamellar interface decays slower with distance from the patterned surface than in thicker films. It is shown that the phenomenological theory can capture many of the same qualitative results as the SCMF simulations for copolymer assembly on substrate patterns with LER, but, at the same time, is limited by an incomplete description of the constraints on the polymer chain conformations imposed by the substrate.Keywords
This publication has 59 references indexed in Scilit:
- Single chain in mean field simulations: Quasi-instantaneous field approximation and quantitative comparison with Monte Carlo simulationsThe Journal of Chemical Physics, 2006
- Microphase Separation in Thin Block Copolymer Films: A Weak Segregation Mean-Field ApproachMacromolecules, 2006
- Dynamics of Terrace Formation in a Nanostructured Thin Block Copolymer FilmLangmuir, 2006
- Symmetric diblock copolymer thin films confined between homogeneous and patterned surfaces: Simulations and theoryThe Journal of Chemical Physics, 2000
- Phase separation of polymer blend films near patterned surfacesThe Journal of Chemical Physics, 1999
- Single-Grain Lamellar Microdomain from a Diblock CopolymerMacromolecules, 1999
- Adsorption Dynamics. Extension of Self-Consistent Field Theory to Dynamical ProblemsMacromolecules, 1997
- Response and instabilities of the lamellar phase of diblock copolymers under uniaxial stressThe Journal of Chemical Physics, 1994
- Modeling copolymer adsorption on laterally heterogeneous surfacesPhysical Review Letters, 1991
- Equilibrium emulsification of polymer blends by diblock copolymersJournal de Physique, 1990