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Hydration-Dependent Hierarchical Structures in Block Copolymer-Surfactant Complex Salts

Ferreira, Guilherme A. ; Piculell, Lennart LU and Loh, Watson LU (2018) In Macromolecules 51(23). p.9915-9924
Abstract

Block copolymer-surfactant "complex salts" (BCPCS), containing one neutral water-soluble block and one polyion/surfactant-ion block, were prepared from poly(acrylamide)-block-poly(acrylic acid) block copolymers by neutralizing the acrylate charges with cationic dodecyl- or hexadecyltrimethylammonium surfactant counterions. The BCPCS were studied in hydrated samples containing 20-99 wt % water (and no additional ions) employing small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), and visual inspection. Selected samples in D2O were also investigated. The results reveal for the first time, for hydrated samples, the formation of ordered hierarchical structures on both block copolymer and surfactant length scales,... (More)

Block copolymer-surfactant "complex salts" (BCPCS), containing one neutral water-soluble block and one polyion/surfactant-ion block, were prepared from poly(acrylamide)-block-poly(acrylic acid) block copolymers by neutralizing the acrylate charges with cationic dodecyl- or hexadecyltrimethylammonium surfactant counterions. The BCPCS were studied in hydrated samples containing 20-99 wt % water (and no additional ions) employing small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), and visual inspection. Selected samples in D2O were also investigated. The results reveal for the first time, for hydrated samples, the formation of ordered hierarchical structures on both block copolymer and surfactant length scales, analogous to structures that have previously been reported for solvent-free block copolymer-surfactant complexes in the solid or melt. The BCPCS structures do not dissolve but display a finite swelling also in the presence of excess water. The structure on the BCP length scale (lamellar or hexagonal) depends only on the BCP, whereas the structure on the CS length scale (hexagonal or micellar cubic) depends on both the surfactant ion and the water content. The results strongly suggest that the observed concentrated hierarchical structures are the equilibrium states for BCPCS in water, although small aggregates formed reproducibly in the dilute regime have been reported for BCPCS and similar systems, collectively known as complex coacervate core micelles (C3Ms).

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publication status
published
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in
Macromolecules
volume
51
issue
23
pages
10 pages
publisher
The American Chemical Society (ACS)
external identifiers
  • scopus:85058296222
ISSN
0024-9297
DOI
10.1021/acs.macromol.8b02053
language
English
LU publication?
yes
id
e97e3c0d-1e07-4795-beda-20b420bd79de
date added to LUP
2019-01-03 12:24:10
date last changed
2020-10-07 06:13:34
@article{e97e3c0d-1e07-4795-beda-20b420bd79de,
  abstract     = {<p>Block copolymer-surfactant "complex salts" (BCPCS), containing one neutral water-soluble block and one polyion/surfactant-ion block, were prepared from poly(acrylamide)-block-poly(acrylic acid) block copolymers by neutralizing the acrylate charges with cationic dodecyl- or hexadecyltrimethylammonium surfactant counterions. The BCPCS were studied in hydrated samples containing 20-99 wt % water (and no additional ions) employing small-angle X-ray scattering (SAXS), dynamic light scattering (DLS), and visual inspection. Selected samples in D<sub>2</sub>O were also investigated. The results reveal for the first time, for hydrated samples, the formation of ordered hierarchical structures on both block copolymer and surfactant length scales, analogous to structures that have previously been reported for solvent-free block copolymer-surfactant complexes in the solid or melt. The BCPCS structures do not dissolve but display a finite swelling also in the presence of excess water. The structure on the BCP length scale (lamellar or hexagonal) depends only on the BCP, whereas the structure on the CS length scale (hexagonal or micellar cubic) depends on both the surfactant ion and the water content. The results strongly suggest that the observed concentrated hierarchical structures are the equilibrium states for BCPCS in water, although small aggregates formed reproducibly in the dilute regime have been reported for BCPCS and similar systems, collectively known as complex coacervate core micelles (C3Ms).</p>},
  author       = {Ferreira, Guilherme A. and Piculell, Lennart and Loh, Watson},
  issn         = {0024-9297},
  language     = {eng},
  number       = {23},
  pages        = {9915--9924},
  publisher    = {The American Chemical Society (ACS)},
  series       = {Macromolecules},
  title        = {Hydration-Dependent Hierarchical Structures in Block Copolymer-Surfactant Complex Salts},
  url          = {http://dx.doi.org/10.1021/acs.macromol.8b02053},
  doi          = {10.1021/acs.macromol.8b02053},
  volume       = {51},
  year         = {2018},
}