1H NMR and small-angle neutron scattering investigation of the structure and solubilization behavior of three-layer nanoparticles

Jaroslav Ǩíž, Josef Pleštil, Herman Pospíšil, Petr Kadlec, Čestmír Koňák, László Almásy, Alexander I. Kuklin

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Three-layer nanoparticles were prepared by radiation-induced polymerization of 1-10 g/L of methyl methacrylate dissolved in a 0.1 wt % D 2O solution of polystyrene-poly(methacrylic acid) (PS-PMA) micelles. According to NMR and small-angle neutron scattering (SANS), most of the poly(methyl methacrylate) (PMMA) is adsorbed at the core-shell interface of the particles. A small fraction of shorter PMMA probably sticks to outer parts of the PMA chains. The absorption kinetics and equilibria of benzene and chloroform were studied by NMR and SANS time-resolved experiments. The diffusion front in the PS core is very narrow but quite broad in the PMMA sheet suggesting, thus, a less compact state of PMMA. According to SANS, the diffusion kinetics is almost independent of the PMMA sheet thickness. In contrast to it, the absorption capacity, reflected by both SANS and NMR, increases markedly with the PMMA content in the particle. The maximum amount of solubilized compound depends on its positive interaction with PMMA (expressed by the χ parameter) but is restricted by the growing interface tension between swollen PMMA and D2O. In accordance with this conclusion, a particle saturated with benzene can absorb chloroform only at the expense of & part of benzene expelled into the surrounding medium and vice versa. Starting with 10 g PMMA/L (10 times the weight of the original micelles), the particles become unstable when being swollen with a good solvent.

Original languageEnglish
Pages (from-to)11255-11263
Number of pages9
JournalLangmuir
Volume20
Issue number25
DOIs
Publication statusPublished - Dec 7 2004

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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