Structure-property relationship in stimulus-responsive bolaamphiphile hydrogels

Langmuir. 2007 Jul 3;23(14):7715-23. doi: 10.1021/la7003479. Epub 2007 Jun 5.

Abstract

The formation of temperature-, concentration-, and pH-responsive hydrogels composed of the symmetric long-chain bolaamphiphile dotriacontane-1,1'-diyl bis[[2-(dimethylammonio)ethyl]phosphate] (Me(2)PE-C32-Me(2)PE) was investigated by rheological, scattering, and spectroscopic techniques. At pH 5, this bolaamphiphile is known to form a dense network of helically structured nanofibers (Köhler et al. Soft Matter 2006, 2, 77-86). Rheological measurements and dynamic light scattering were used to describe the macroscopic behavior of the hydrogels. Small-angle neutron scattering (SANS) and time-resolved static light scattering were applied to get information about the morphology of the self-assembled aggregates. Finally, solid-state 31P NMR spectroscopy was used to gain insight into the mobility of the bolaamphiphile molecules within the fiber aggregates. In comparison with the previously examined trimethylammonio analogue PC-C32-PC, which forms temperature-dependent hydrogels, Me(2)PE-C32-Me(2)PE exhibits additional concentration- and pH-dependent gelling properties. The significantly higher stability of the Me(2)PE-C32-Me(2)PE hydrogel is supported by the SANS data, which indicate the presence of fiber aggregates up to 50 degrees C.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkanes
  • Diacetyl / analogs & derivatives*
  • Hydrogels / chemistry*
  • Hydrogen-Ion Concentration
  • Magnetic Resonance Spectroscopy
  • Methylamines / chemistry
  • Neutrons
  • Rheology
  • Scattering, Small Angle
  • Temperature

Substances

  • Alkanes
  • Hydrogels
  • Methylamines
  • dotriacontane
  • Diacetyl
  • trimethylamine