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Molecular Assembly in Block Copolymer-Surfactant Nanoparticle Dispersions: Information on Molecular Exchange and Apparent Solubility from High-Resolution and PFG NMR.
Ferreira, Guilherme A; Loh, Watson; Topgaard, Daniel; Söderman, Olle; Piculell, Lennart.
Afiliação
  • Ferreira GA; Institute of Chemistry, University of Campinas (UNICAMP), P.O. Box 6154, Campinas 13083-970, Brazil.
  • Loh W; Institute of Chemistry, University of Campinas (UNICAMP), P.O. Box 6154, Campinas 13083-970, Brazil.
  • Topgaard D; Division of Physical Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden.
  • Söderman O; Division of Physical Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden.
  • Piculell L; Division of Physical Chemistry, Lund University, P.O. Box 124, 22100 Lund, Sweden.
Polymers (Basel) ; 13(19)2021 Sep 25.
Article em En | MEDLINE | ID: mdl-34641081
Internally structured block copolymer-surfactant particles are formed when the complex salts of ionic-neutral block copolymers neutralized by surfactant counterions are dispersed in aqueous media. Here, we report the 1H NMR signal intensities and self-diffusion coefficients (D, from pulsed field gradient nuclear magnetic resonance, PFG NMR) of trimethyl alkylammonium surfactant ions and the poly(acrylamide)-block-poly(acrylate) (PAAm-b-PA) polyions forming such particles. The results reveal the presence of an "NMR-invisible" (slowly exchanging) fraction of aggregated surfactant ions in the particle core and an "NMR-visible" fraction consisting of surface surfactant ions in rapid exchange with the surfactant ions dissociated into the aqueous domain. They also confirm that the neutral PAAm blocks are exposed to water at the particle surface, while the PA blocks are buried in the particle core. The self-diffusion of the polyions closely agree with the self-diffusion of a hydrophobic probe molecule solubilized in the particles, showing that essentially all copolymer chains are incorporated in the aggregates. Through centrifugation, we prepared macroscopically phase-separated systems with a phase concentrated in particles separated from a clear dilute phase. D values for the surfactant and block copolymer indicated that the dilute phase contained small aggregates (ca. 5 nm) of surfactant ions and a few anionic-neutral block copolymer chains. Regardless of the overall concentration of the sample, the fraction of block copolymer found in the dilute phase was nearly constant. This indicates that the dilute fraction represented a tail of small particles created by the dispersion process rather than a true thermodynamic solubility of the complex salts.
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Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Revista: Polymers (Basel) Ano de publicação: 2021 Tipo de documento: Article País de afiliação: Brasil País de publicação: Suíça
Texto completo
Adicionar na Minha BVS
Imprimir
XML
PubMed Links
Buscar no Google

Texto completo: 1 Coleções: 01-internacional Base de dados: MEDLINE Idioma: En Revista: Polymers (Basel) Ano de publicação: 2021 Tipo de documento: Article País de afiliação: Brasil País de publicação: Suíça