Polystyrene Latex Nanoparticles Shrink When Polyelectrolyte of the Same Charge is Added

Sangmin Jeon, Steve Granick

Research output: Contribution to journalArticlepeer-review


Reversible deswelling of latex nanoparticles, induced by electrostatic repulsion after adding polyelectrolyte (polystyrenesulfonate, PSS) chains of the same charge to suspensions of the particles in deionized water, is shown using time-resolved fluorescence depolarization of fluorescent dyes (Lumogen 5 Yellow 083) impregnated within the nanoparticles, using methods of two-photon excitation. Shrinkage of the particles produced closer spacing between dyes, thus enhancing fluorescence quenching and homo energy transfer, which depolarizes fluorescence emission. Thus, it was observed that the higher the PSS concentration, the more rapid decay of fluorescence depolarization on the subnanosecond time scale. When NaCl was subsequently added, screening caused the original particle size to be recovered. Tentatively, the diameter increase was roughly 7%. The spatial resolution provided by two-photon excitation implies that this method can be used to estimate the size changes of particles in situ in concentrated semiturbid solutions.

Original languageEnglish (US)
Pages (from-to)2919-2923
Number of pages5
Issue number8
StatePublished - Apr 20 2004

ASJC Scopus subject areas

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


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