On the rheology of mixed systems of hydrophobically modified polyacrylate microgels and surfactants: Role of the surfactant architecture

Luís Alves, Björn Lindman, Björn Klotz, Axel Böttcher, Hans Martin Haake, Filipe E. Antunes

Research output: Contribution to journalArticlepeer-review

13 Citations (SciVal)

Abstract

Hypothesis The rheological control of suspensions is of key interest in the formulation design. A chemically cross-linked hydrophobically modified poly(acrylic acid) (HMCL-PAA), used as rheology modifier, is pH sensitive and shows swelling behavior above a critical pH due to the ionization of the acrylic acid groups. At low pH, HMCL-PAA suspensions are liquid and turbid. The binding of surfactants to HMCL-PAA, at low pH conditions, can result in significant changes on rheology and transparency of the polymeric suspensions, due to the swelling of the microgel particles. Experiments The influence of surfactants addition on the rheological properties and transparency of HMCL-PAA suspensions was determined. A systematic study was performed using different types of surfactants (ionic, non-ionic and zwitterionic). Findings The gelation efficiency of HMCL-PAA suspensions at low pH is strongly dependent on surfactant architecture: ionic surfactants are found to be much more efficient than non-ionic or zwitterionic surfactants. Ionic surfactants lead to a liquid-to-gel transition accompanied by an increase of transparency of the suspensions. Among the ionic surfactants, anionics show stronger interactions with the polymer. Also the surfactant hydrophobicity is relevant; the more hydrophobic the surfactant, the stronger is the binding to the polymer and thus the larger the particle swelling.

Original languageEnglish
Pages (from-to)489-496
Number of pages8
JournalJournal of Colloid and Interface Science
Volume513
DOIs
Publication statusPublished - 2018 Mar 1

Subject classification (UKÄ)

  • Polymer Chemistry

Keywords

  • Crosslinked polymer
  • Gelation
  • Hydrophobic association
  • Poly(acrylic acid) derivative
  • Polymer/surfactant association
  • Surfactant binding

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