Electrostatic self-assembly of neutral and polyelectrolyte block copolymers and oppositely charged surfactant

Annaka Masahiko, Kanae Morishita, Satoshi Okabe

研究成果: ジャーナルへの寄稿記事

45 引用 (Scopus)

抄録

We investigated the phase behavior and the microscopic structure of the colloidal complexes constituted from neutral/polyelectrolyte diblock copolymers and oppositely charged surfactant by dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The neutral block is poly(N- isopropylacrylamide) (PNIPAM), and the polyelectrolyte block is negatively charged poly(acrylic acid) (PAA). In aqueous solution with neutral pH, PAA behaves as a weak polyelectrolyte, whereas PNIPAM is neutral and in good-solvent condition at ambient temperature, but in poor-solvent condition above ∼32 °C. This block copolymer, PNIPAM-b-PAA with a narrow polydispersity, is studied in aqueous solution with an anionic surfactant, dodecyltrimethylammonium bromide (DTAB). For a low surfactant-to-polymer charge ratio Z lower than the critical value Zc, the colloidal complexes are single DTAB micelles dressed by a few PNIPAM-b-PAA. Above Zc, the colloidal complexes form a core-shell microstructure. The core of the complex consists of densely packed DTA+ micelles, most likely connected between them by PAA blocks. The intermicellar distance of the DTA+ micelles is ∼39 Å, which is independent of the charge ratio Z as well as the temperature. The corona of the complex is constituted from the thermosensitive PNIPAM. At lower temperature the macroscopic phase separation is hindered by the swollen PNIPAM chains. Above the critical temperature Tc, the PNIPAM corona collapses leading to hydrophobic aggregates of the colloidal complexes.

元の言語英語
ページ(範囲)11700-11707
ページ数8
ジャーナルJournal of Physical Chemistry B
111
発行部数40
DOI
出版物ステータス出版済み - 10 11 2007

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Polyelectrolytes
block copolymers
Static Electricity
Surface-Active Agents
Self assembly
Block copolymers
self assembly
Electrostatics
micelles
Surface active agents
surfactants
Micelles
electrostatics
coronas
bromides
thermal analysis
Differential thermal analysis
aqueous solutions
acrylic acid
Temperature

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

これを引用

Electrostatic self-assembly of neutral and polyelectrolyte block copolymers and oppositely charged surfactant. / Masahiko, Annaka; Morishita, Kanae; Okabe, Satoshi.

:: Journal of Physical Chemistry B, 巻 111, 番号 40, 11.10.2007, p. 11700-11707.

研究成果: ジャーナルへの寄稿記事

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abstract = "We investigated the phase behavior and the microscopic structure of the colloidal complexes constituted from neutral/polyelectrolyte diblock copolymers and oppositely charged surfactant by dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The neutral block is poly(N- isopropylacrylamide) (PNIPAM), and the polyelectrolyte block is negatively charged poly(acrylic acid) (PAA). In aqueous solution with neutral pH, PAA behaves as a weak polyelectrolyte, whereas PNIPAM is neutral and in good-solvent condition at ambient temperature, but in poor-solvent condition above ∼32 °C. This block copolymer, PNIPAM-b-PAA with a narrow polydispersity, is studied in aqueous solution with an anionic surfactant, dodecyltrimethylammonium bromide (DTAB). For a low surfactant-to-polymer charge ratio Z lower than the critical value Zc, the colloidal complexes are single DTAB micelles dressed by a few PNIPAM-b-PAA. Above Zc, the colloidal complexes form a core-shell microstructure. The core of the complex consists of densely packed DTA+ micelles, most likely connected between them by PAA blocks. The intermicellar distance of the DTA+ micelles is ∼39 {\AA}, which is independent of the charge ratio Z as well as the temperature. The corona of the complex is constituted from the thermosensitive PNIPAM. At lower temperature the macroscopic phase separation is hindered by the swollen PNIPAM chains. Above the critical temperature Tc, the PNIPAM corona collapses leading to hydrophobic aggregates of the colloidal complexes.",
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