Environmentally responsive nanoparticles from block ionomer complexes: Effects of pH and ionic strength

Sergey V. Solomatin, Tatiana K. Bronich, Tom W. Bargar, Adi Eisenberg, Victor A. Kabanov, Alexander V. Kabanov

Research output: Contribution to journalArticlepeer-review

104 Scopus citations


Nanoscale size materials, displaying environmentally responsive behavior, are of special interest for various applications, including drug delivery. This work explores the effects of environmental parameters (pH, concentration, and chemical nature of low molecular weight salts) on self-assembly and physicochemical properties of block ionomer complexes (BIC). BIC are synthesized by reacting block ionomer (PEO-b-PMA) and oppositely charged surfactant (hexadecyltrimethylammonium bromide). The resulted BIC form stable aqueous dispersions at any ionomer/surfactant ratio (particle size in the 60-90 nm range). Decrease of the ionization degree of the PMA block upon decrease of pH causes elevation of particle size at pH < 5.5 followed by formation of large aggregates at pH < 4. Increase of pH causes a decrease of the particle size. Addition of low molecular weight salts leads to disintegration of BIC at a specific salt concentration termed the "critical salt concentration" or csc. The csc values strongly depend on the nature of the salt. For cations csc increases in the order K+ ≈ Li+ ≈ Na+ gt; N(CH3)4+. For anions it increases in the order I- > Br- > Cl- > AcO- > F-. Such behavior is explained by the contribution of binding of counterions with PMA segments and surfactant cations. The disintegration process is reversible, as BIC particles reconstitute as the salt concentration decreases.

Original languageEnglish (US)
Pages (from-to)8069-8076
Number of pages8
Issue number19
StatePublished - Sep 16 2003

ASJC Scopus subject areas

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


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