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Title: Beyond native block copolymer morphologies

Abstract

Block copolymers self-assemble into a range of canonical morphologies. Here, we review a broad range of techniques for inducing these materials to form structures beyond the ‘native’ morphologies seen in the bulk equilibrium phase diagram. Methods that exploit intrinsic encoding (molecular design) and external enforcement (directed assembly) are compared.

Authors:
ORCiD logo [1]; ORCiD logo [1]
  1. Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States). Center for Functional Nanomaterials (CFN)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1399668
Report Number(s):
BNL-114375-2017-JA
Journal ID: ISSN 2058-9689; MSDEBG; KC0403020
Grant/Contract Number:
SC0012704
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Molecular Systems Design & Engineering
Additional Journal Information:
Journal Volume: 2; Journal Issue: 5; Journal ID: ISSN 2058-9689
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 77 NANOSCIENCE AND NANOTECHNOLOGY; block copolymer; self-assembly; Center for Functional Nanomaterials

Citation Formats

Doerk, Gregory S., and Yager, Kevin G. Beyond native block copolymer morphologies. United States: N. p., 2017. Web. doi:10.1039/c7me00069c.
Doerk, Gregory S., & Yager, Kevin G. Beyond native block copolymer morphologies. United States. doi:10.1039/c7me00069c.
Doerk, Gregory S., and Yager, Kevin G. Wed . "Beyond native block copolymer morphologies". United States. doi:10.1039/c7me00069c.
@article{osti_1399668,
title = {Beyond native block copolymer morphologies},
author = {Doerk, Gregory S. and Yager, Kevin G.},
abstractNote = {Block copolymers self-assemble into a range of canonical morphologies. Here, we review a broad range of techniques for inducing these materials to form structures beyond the ‘native’ morphologies seen in the bulk equilibrium phase diagram. Methods that exploit intrinsic encoding (molecular design) and external enforcement (directed assembly) are compared.},
doi = {10.1039/c7me00069c},
journal = {Molecular Systems Design & Engineering},
number = 5,
volume = 2,
place = {United States},
year = {Wed Sep 20 00:00:00 EDT 2017},
month = {Wed Sep 20 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
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  • Self-assembly is a powerful paradigm, wherein molecules spontaneously form ordered phases exhibiting well-defined nanoscale periodicity and shapes. However, the inherent energy-minimization aspect of self-assembly yields a very limited set of morphologies, such as lamellae or hexagonally packed cylinders. Here, we show how soft self-assembling materials—block copolymer thin films—can be manipulated to form a diverse library of previously unreported morphologies. In this iterative assembly process, each polymer layer acts as both a structural component of the final morphology and a template for directing the order of subsequent layers. Specifically, block copolymer films are immobilized on surfaces, and template successive layers throughmore » subtle surface topography. As a result, this strategy generates an enormous variety of three-dimensional morphologies that are absent in the native block copolymer phase diagram.« less
  • No abstract prepared.
  • In this paper we describe dewetting phenomena in organic (polystyrene, PS)/inorganic (polyferrocenyldimethylsilane, PFS) block copolymer thin films. Mesoscale dendritic structures are induced when the spin-cast thin film of this polymer is subjected to so-called hybrid annealing, which involves both thermal and solvent annealing. We show that the development and arrangement of these mesoscale dendritic structures depends on the initial film thickness in addition to the annealing time. Importantly, there are two criteria that must be fulfilled to achieve these mesoscale morphologies: (i) the film has to be subjected to hybrid annealing, i.e. either only thermal or only solvent annealing doesmore » not produce any notable mesostructures and (ii) both PS and PFS blocks must be present during the thermal and solvent annealing procedures; if one of the blocks, for instance PS, is removed before annealing then there is no mesostructure. Various possible mechanisms for the formation of these structures are discussed and results indicate that the PFS block dominates the structure formation. We also observe a ring- or worm-like nanostructure which develops only when the film is subjected to hybrid annealing at a particular film thickness. Apart from these results, here we demonstrate that mesoscale structures can be successfully transferred onto underlying substrates.« less
  • Poly(styrene-block-ferrocenyldimethylsilane) (PS-b-PFS) is a metal-containing block copolymer that exhibits certain advantages as a mask for lithographic applications. These advantages include compatibility with a wide range of substrates, ease of control over domain morphologies and robust stability to etch plasma, which aid in the development of high-aspect-ratio patterns. An asymmetric cylinder-forming PS-b-PFS copolymer is subjected to different processing to manipulate the morphology of the phase-separated domains. Control of film structure and domain morphology is achieved by adjusting the film thickness, mode of annealing, and/or annealing time. Changing the process from thermal or solvent annealing to hybrid annealing (thermal and then solventmore » annealing in sequence) leads to the formation of mesoscale spherulitic and dendritic morphologies. In this communication, we show that reversing the order of the hybrid annealing (solvent annealing first and then thermal annealing) of relatively thick films (>100 nm) on homogeneously thick substrates develops disordered lamellar structure. Furthermore, the same processing applied on a substrate with a thin, mechanically flexible window in the center leads to the formation of sub-micron scale concentric ring patterns. Enhanced material mobility in the thick film during hybrid annealing along with dynamic rippling effects that may arise from the vibration of the thin window during spin casting are likely causes for these morphologies.« less