Insights into the interactions among surfactin, betaines, and PAM: Surface tension, small-Angle neutron scattering, and small-Angle x-ray scattering study

Jingwen Xiao, Fang Liu, Vasil M. Garamus, László Almásy, Ulrich A. Handge, Regine Willumeit, Bozhong Mu, Aihua Zou

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

The interactions among neutral polymer polyacrylamide (PAM) and the biosurfactant Surfactin and four betaines, N-dodecyl-N,N-dimethyl-3-Ammonio-1- propanesulfonate (SDDAB), N-tetradecyl-N,N-dimethyl-3-Ammonio-1-propanesulfonate (STDAB), N-hexadecyl-N,N-dimethyl-3-Ammonio-1-propanesulfonate (SHDAB), and N-dodecyl-N,N-dimethyl-2-Ammonio-Acetate (C12BE), in phosphate buffer solution (PBS) have been studied by surface tension measurements, small-Angle neutron scattering (SANS), small-Angle X-ray scattering (SAXS), and rheological experiments. It has been confirmed that the length of alkyl chain is a key parameter of interaction between betaines and PAM. Differences in scattering contrast between X-ray and neutrons for surfactants and PAM molecules provide the opportunity to separately follow the changes of structure of PAM and surfactant aggregates. At concentrations of betaines higher than CMC (critical micelle concentration) and C2 (CMC of surfactant with the presence of polymer), spherical micelles are formed in betaines and betaines/PAM solutions. Transition from spherical to rod-like aggregates (micelles) has been observed in solutions of Surfactin and Surfactin/SDDAB (αSurfactin = 0.67 (molar fraction)) with addition of 0.8 wt % of PAM. The conformation change of PAM molecules only can be observed for Surfactin/SDDAB/PAM system. Viscosity values follow the structural changes suggested from scattering measurements i.e., gradually increases for mixtures PAM → Surfactin/PAM → Surfactin/SDDAB/PAM in PBS.

Original languageEnglish
Pages (from-to)3363-3372
Number of pages10
JournalLangmuir
Volume30
Issue number12
DOIs
Publication statusPublished - Apr 1 2014

ASJC Scopus subject areas

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

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