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Title: In-plane and out-of-plane defectivity in thin films of lamellar block copolymers

We investigate the ordering of poly(styrene-b-methyl methacrylate) (PS-PMMA) lamellar copolymers (periodicity L 0 = 46 nm) confined between a free surface and brushed poly(styrene-r-methyl methacrylate) silicon substrate. The processing temperature was selected to eliminate wetting layers at the top and bottom interfaces, producing approximately neutral boundaries that stabilize perpendicular domain orientations. The PS-PMMA film thickness (t = 0.5L 0–2.5L 0) and brush grafting density (Σ = 0.2–0.6 nm –2) were systematically varied to examine their impacts on in-plane and out-of-plane ordering. Samples were characterized with a combination of high-resolution microscopy, X-ray reflectivity, and grazing-incidence small-angle X-ray scattering. In-plane order at the top of the film (quantified through calculation of orientational correlation lengths) improved with t n, where the exponent n increased from 0.75 to 1 as Σ decreased from 0.6 to 0.2 nm –2. Out-of-plane defects such as tilted domains were detected in all films, and the distribution of domain tilt angles was nearly independent of t and Σ. These studies demonstrate that defectivity in perpendicular lamellar phases is three-dimensional, comprised of in-plane topological defects and out-of-plane domain tilt, with little or no correlation between these two types of disorder. As a result, strong interactions between the block copolymer andmore » underlying substrate may trap both kinds of thermally generated defects.« less
Authors:
 [1] ;  [1] ;  [1] ;  [2] ; ORCiD logo [1]
  1. Univ. of Houston, Houston, TX (United States)
  2. Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Grant/Contract Number:
AC02-06CH11357
Type:
Accepted Manuscript
Journal Name:
Journal of Polymer Science. Part B, Polymer Physics
Additional Journal Information:
Journal Volume: 54; Journal Issue: 2; Journal ID: ISSN 0887-6266
Publisher:
Wiley
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
National Science Foundation (NSF); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; block copolymers; defectivity; directed self-assembly; grazing-incidence small angle X-ray scattering; thin films
OSTI Identifier:
1339952

Mahadevapuram, Nikhila, Mitra, Indranil, Bozhchenko, Alona, Strzalka, Joseph, and Stein, Gila E. In-plane and out-of-plane defectivity in thin films of lamellar block copolymers. United States: N. p., Web. doi:10.1002/polb.23937.
Mahadevapuram, Nikhila, Mitra, Indranil, Bozhchenko, Alona, Strzalka, Joseph, & Stein, Gila E. In-plane and out-of-plane defectivity in thin films of lamellar block copolymers. United States. doi:10.1002/polb.23937.
Mahadevapuram, Nikhila, Mitra, Indranil, Bozhchenko, Alona, Strzalka, Joseph, and Stein, Gila E. 2015. "In-plane and out-of-plane defectivity in thin films of lamellar block copolymers". United States. doi:10.1002/polb.23937. https://www.osti.gov/servlets/purl/1339952.
@article{osti_1339952,
title = {In-plane and out-of-plane defectivity in thin films of lamellar block copolymers},
author = {Mahadevapuram, Nikhila and Mitra, Indranil and Bozhchenko, Alona and Strzalka, Joseph and Stein, Gila E.},
abstractNote = {We investigate the ordering of poly(styrene-b-methyl methacrylate) (PS-PMMA) lamellar copolymers (periodicity L0 = 46 nm) confined between a free surface and brushed poly(styrene-r-methyl methacrylate) silicon substrate. The processing temperature was selected to eliminate wetting layers at the top and bottom interfaces, producing approximately neutral boundaries that stabilize perpendicular domain orientations. The PS-PMMA film thickness (t = 0.5L0–2.5L0) and brush grafting density (Σ = 0.2–0.6 nm–2) were systematically varied to examine their impacts on in-plane and out-of-plane ordering. Samples were characterized with a combination of high-resolution microscopy, X-ray reflectivity, and grazing-incidence small-angle X-ray scattering. In-plane order at the top of the film (quantified through calculation of orientational correlation lengths) improved with tn, where the exponent n increased from 0.75 to 1 as Σ decreased from 0.6 to 0.2 nm–2. Out-of-plane defects such as tilted domains were detected in all films, and the distribution of domain tilt angles was nearly independent of t and Σ. These studies demonstrate that defectivity in perpendicular lamellar phases is three-dimensional, comprised of in-plane topological defects and out-of-plane domain tilt, with little or no correlation between these two types of disorder. As a result, strong interactions between the block copolymer and underlying substrate may trap both kinds of thermally generated defects.},
doi = {10.1002/polb.23937},
journal = {Journal of Polymer Science. Part B, Polymer Physics},
number = 2,
volume = 54,
place = {United States},
year = {2015},
month = {10}
}