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Title: Defect Annihilation Pathways in Directed Assembly of Lamellar Block Copolymer Thin Films

Abstract

Defects in highly ordered self-assembled block copolymers represent an important roadblock toward the adoption of these materials in a wide range of applications. This work examines the pathways for annihilation of defects in symmetric diblock copolymers in the context of directed assembly using patterned substrates. Past theoretical and computational studies of such systems have predicted minimum free energy pathways that are characteristic of an activated process. However, they have been limited to adjacent dislocations with opposite Burgers vectors. By relying on a combination of advanced sampling techniques and particle-based simulations, this work considers the long-range interaction between dislocation pairs, both on homogeneous and nanopatterned substrates. As illustrated here, these interactions are central to understanding the defect structures that are most commonly found in applications and in experimental studies of directed self-assembly. More specifically, it is shown that, for dislocation dipoles separated by several lamellae, multiple consecutive free energy barriers lead to effective kinetic barriers that are an order of magnitude larger than those originally reported in the literature for tightly bound dislocation pairs. Furthermore, it is also shown that annihilation pathways depend strongly on both the separation between dislocations and their relative position with respect to the substrate guiding stripesmore » used to direct the assembly.« less

Authors:
ORCiD logo [1];  [2]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [4]
  1. Chonnam National Univ., Gwangju (Korea)
  2. Chonnam National Univ., Gwangju (Korea); The Univ. of Chicago, Chicago, IL (United States)
  3. Argonne National Lab. (ANL), Argonne, IL (United States); The Univ. of Texas at San Antonio, San Antonio, TX (United States)
  4. The Univ. of Chicago, Chicago, IL (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1487452
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Accepted Manuscript
Journal Name:
ACS Nano
Additional Journal Information:
Journal Volume: 12; Journal Issue: 10; Journal ID: ISSN 1936-0851
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; block copolymer; defect annihilation; directed assembly; minimum free energy path; string method

Citation Formats

Hur, Su -Mi, Thapar, Vikram, Ramírez-Hernández, Abelardo, Nealey, Paul F., and de Pablo, Juan J. Defect Annihilation Pathways in Directed Assembly of Lamellar Block Copolymer Thin Films. United States: N. p., 2018. Web. doi:10.1021/acsnano.8b04202.
Hur, Su -Mi, Thapar, Vikram, Ramírez-Hernández, Abelardo, Nealey, Paul F., & de Pablo, Juan J. Defect Annihilation Pathways in Directed Assembly of Lamellar Block Copolymer Thin Films. United States. doi:10.1021/acsnano.8b04202.
Hur, Su -Mi, Thapar, Vikram, Ramírez-Hernández, Abelardo, Nealey, Paul F., and de Pablo, Juan J. Tue . "Defect Annihilation Pathways in Directed Assembly of Lamellar Block Copolymer Thin Films". United States. doi:10.1021/acsnano.8b04202. https://www.osti.gov/servlets/purl/1487452.
@article{osti_1487452,
title = {Defect Annihilation Pathways in Directed Assembly of Lamellar Block Copolymer Thin Films},
author = {Hur, Su -Mi and Thapar, Vikram and Ramírez-Hernández, Abelardo and Nealey, Paul F. and de Pablo, Juan J.},
abstractNote = {Defects in highly ordered self-assembled block copolymers represent an important roadblock toward the adoption of these materials in a wide range of applications. This work examines the pathways for annihilation of defects in symmetric diblock copolymers in the context of directed assembly using patterned substrates. Past theoretical and computational studies of such systems have predicted minimum free energy pathways that are characteristic of an activated process. However, they have been limited to adjacent dislocations with opposite Burgers vectors. By relying on a combination of advanced sampling techniques and particle-based simulations, this work considers the long-range interaction between dislocation pairs, both on homogeneous and nanopatterned substrates. As illustrated here, these interactions are central to understanding the defect structures that are most commonly found in applications and in experimental studies of directed self-assembly. More specifically, it is shown that, for dislocation dipoles separated by several lamellae, multiple consecutive free energy barriers lead to effective kinetic barriers that are an order of magnitude larger than those originally reported in the literature for tightly bound dislocation pairs. Furthermore, it is also shown that annihilation pathways depend strongly on both the separation between dislocations and their relative position with respect to the substrate guiding stripes used to direct the assembly.},
doi = {10.1021/acsnano.8b04202},
journal = {ACS Nano},
number = 10,
volume = 12,
place = {United States},
year = {2018},
month = {9}
}

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Cited by: 5 works
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Figures / Tables:

Fig. 1 Fig. 1: MFEP between a dislocation dipole separated by two periods and defectfree lamellar structures. (A) Free-energy difference, $∆F$ , as a function of reaction coordinate, $α$. (B) Several representative morphologies (top-down and bottom-up views) along the pathway. The top views for the initial and final morphologies of the equilibriummore » pathway are also shown. (C) Three-dimensional view of the morphology corresponding to the first (t1) and the second transition state (t2).« less

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Figures/Tables have been extracted from DOE-funded journal article accepted manuscripts.