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Micro- and nanophase separations in hierarchical self-assembly of strongly amphiphilic block copolymer-based ionic supramolecules

Asad Ayoubi, Mehran LU ; Zhu, Kaizheng ; Nystrom, Bo ; Almdal, Kristoffer ; Olsson, Ulf LU and Piculell, Lennart LU (2013) In Soft Matter 9(5). p.1540-1555
Abstract
By a selective complexation between different alkyltrimethylammonium amphiphiles (C8, C12 and C16) and three different diblock copolymer systems of poly(styrene)-b-poly(methacrylic acid) at various grafting densities X (X = number of alkyl chains per acidic group of the poly(methacrylic acid) PMAA block), a class of ionic supramolecules are successfully synthesized whose molecular architecture consists of a poly(styrene) PS block (Linear block) covalently connected to a strongly amphiphilic comb-like block (AmphComb block), i.e. Linear-b-AmphComb. In the melt state, these ionic supramolecules can show simultaneous microphase (between Linear and AmphComb blocks) and nanophase (within the AmphComb blocks) separations. This leads to the... (More)
By a selective complexation between different alkyltrimethylammonium amphiphiles (C8, C12 and C16) and three different diblock copolymer systems of poly(styrene)-b-poly(methacrylic acid) at various grafting densities X (X = number of alkyl chains per acidic group of the poly(methacrylic acid) PMAA block), a class of ionic supramolecules are successfully synthesized whose molecular architecture consists of a poly(styrene) PS block (Linear block) covalently connected to a strongly amphiphilic comb-like block (AmphComb block), i.e. Linear-b-AmphComb. In the melt state, these ionic supramolecules can show simultaneous microphase (between Linear and AmphComb blocks) and nanophase (within the AmphComb blocks) separations. This leads to the formation of various structure-in-structure two-scale hierarchical self-assemblies, including S-in-S-LL, S-in-S-BCC, S-in-C, S-in-L and C-in-L, where S, S-LL, S-BCC, C and L stand for spherical, spherical in liquid-like state, spherical in body-centered-cubic arrangement, cylindrical and lamellar, respectively. Synchrotron small angle X-ray scattering (SAXS) and crossed polarizers, together with SAXS modelling analysis, were used for a detailed structural study of the samples. The morphology of the microphase separated state was mapped out on 'master' microdomain morphology diagrams as a function of the volume fraction of the AmphComb blocks (Phi(AmphComb)) and the compositional window of each microdomain morphology was determined. It was observed that, (i) within samples based on the same parent diblock copolymer system, the occurrence of a specific microdomain morphology is only dependent on the value of Phi(AmphComb), regardless of the grafting density X and the length of the alkyl side-chains, and (ii) microdomain morphological boundaries occur at Phi(AmphComb) values of similar to 0.20 (S-LL/C and S-BCC/C) and similar to 0.28 (C/L). Finally, the specific influences of the strongly amphiphilic nature of the AmphComb blocks on the observed morphological and hierarchical behaviours of our system are discussed. For reference, stoichiometric strongly amphiphilic comb-like (AmphComb) ionic supramolecules, based on complexation between a homopolymer of PMAA and the various alkyltrimethylammonium amphiphiles, were prepared, which nanophase separated into S (C8) or C (C12 and C16) domains. (Less)
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author
; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Soft Matter
volume
9
issue
5
pages
1540 - 1555
publisher
Royal Society of Chemistry
external identifiers
  • wos:000312945200017
  • scopus:84872054747
ISSN
1744-6848
DOI
10.1039/c2sm27113c
language
English
LU publication?
yes
id
4fc8f785-48c3-4ac8-b6ee-65b0aed5bc86 (old id 3481369)
date added to LUP
2016-04-01 14:57:19
date last changed
2022-03-29 23:37:08
@article{4fc8f785-48c3-4ac8-b6ee-65b0aed5bc86,
  abstract     = {{By a selective complexation between different alkyltrimethylammonium amphiphiles (C8, C12 and C16) and three different diblock copolymer systems of poly(styrene)-b-poly(methacrylic acid) at various grafting densities X (X = number of alkyl chains per acidic group of the poly(methacrylic acid) PMAA block), a class of ionic supramolecules are successfully synthesized whose molecular architecture consists of a poly(styrene) PS block (Linear block) covalently connected to a strongly amphiphilic comb-like block (AmphComb block), i.e. Linear-b-AmphComb. In the melt state, these ionic supramolecules can show simultaneous microphase (between Linear and AmphComb blocks) and nanophase (within the AmphComb blocks) separations. This leads to the formation of various structure-in-structure two-scale hierarchical self-assemblies, including S-in-S-LL, S-in-S-BCC, S-in-C, S-in-L and C-in-L, where S, S-LL, S-BCC, C and L stand for spherical, spherical in liquid-like state, spherical in body-centered-cubic arrangement, cylindrical and lamellar, respectively. Synchrotron small angle X-ray scattering (SAXS) and crossed polarizers, together with SAXS modelling analysis, were used for a detailed structural study of the samples. The morphology of the microphase separated state was mapped out on 'master' microdomain morphology diagrams as a function of the volume fraction of the AmphComb blocks (Phi(AmphComb)) and the compositional window of each microdomain morphology was determined. It was observed that, (i) within samples based on the same parent diblock copolymer system, the occurrence of a specific microdomain morphology is only dependent on the value of Phi(AmphComb), regardless of the grafting density X and the length of the alkyl side-chains, and (ii) microdomain morphological boundaries occur at Phi(AmphComb) values of similar to 0.20 (S-LL/C and S-BCC/C) and similar to 0.28 (C/L). Finally, the specific influences of the strongly amphiphilic nature of the AmphComb blocks on the observed morphological and hierarchical behaviours of our system are discussed. For reference, stoichiometric strongly amphiphilic comb-like (AmphComb) ionic supramolecules, based on complexation between a homopolymer of PMAA and the various alkyltrimethylammonium amphiphiles, were prepared, which nanophase separated into S (C8) or C (C12 and C16) domains.}},
  author       = {{Asad Ayoubi, Mehran and Zhu, Kaizheng and Nystrom, Bo and Almdal, Kristoffer and Olsson, Ulf and Piculell, Lennart}},
  issn         = {{1744-6848}},
  language     = {{eng}},
  number       = {{5}},
  pages        = {{1540--1555}},
  publisher    = {{Royal Society of Chemistry}},
  series       = {{Soft Matter}},
  title        = {{Micro- and nanophase separations in hierarchical self-assembly of strongly amphiphilic block copolymer-based ionic supramolecules}},
  url          = {{http://dx.doi.org/10.1039/c2sm27113c}},
  doi          = {{10.1039/c2sm27113c}},
  volume       = {{9}},
  year         = {{2013}},
}