Size invariance of polyelectrolyte dendrimers

Giovanni Nisato, Robert Ivkov, Eric J. Amis

Research output: Contribution to journalArticlepeer-review

Abstract

To quantify the swelling response of polyelectrolyte dendrimers in aqueous solutions as affected by changes in solution conditions, we have studied eighth generation, G8, poly(amidoamine) (PAMAM) dendrimers in D2O using small-angle neutron scattering. The charge density is manipulated by varying the pH of the solution in order to protonate and deprotonate the primary and tertiary amines. The coherent scattered intensity at high q values yields size information from the form factor of individual dendrimers. The distance distribution functions of the dendrimers in a variety of experimental situations were determined by indirect Fourier transform. For all the conditions studied, we find that the size of G8 dendrimers is essentially insensitive to variations of the pH (4.7 < pH < 10.1) and of ionic strength (up to 3 M of NaCl). In all cases, the scattering curves yield density profiles that correspond well to a uniform sphere with a radius of gyration RG = 4.0 ± 0.15 nm. We conclude that the dendrimer size is essentially independent of the charge density or ionic strength of the solvent, contrary to the predictions of current models and simulations.

Original languageEnglish (US)
Pages (from-to)4172-4176
Number of pages5
JournalMacromolecules
Volume33
Issue number11
DOIs
StatePublished - May 30 2000
Externally publishedYes

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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