Effects of organic solvents on the scission energy of rodlike micelles

Wanwipa Siriwatwechakul, Terry LaFleur, Robert K. Prud'homme, Phillip Sullivan

Research output: Contribution to journalArticle

45 Scopus citations

Abstract

The linear viscoelastic response of erucyl bis(hydroxyethyl) methylammonium chloride with added KCl has been studied as a function of temperature and nonpolar solvent addition. The plateau modulus is independent of temperature from 25 to 40°C, in contrast to previous studies with salicylate counterions that showed a plateau modulus increasing with temperature over this range. The average micelle length, L, predicted by the model of Cates, depends experimentally on E scisk- BT, where 2 scis is the scission energy of the chain and k BT is the Boltzmann constant times the absolute temperature. With ethanol addition, the calculated average contour length, ̄L, decreases by a factor of 4 as ethanol concentration varies from 0 to 1.3 M. This corresponds to an apparent energy for scission, E scis, decrease from 81 ± 8 to 74 ± 7 kJ/mol. On the other hand, only 80 mM of hexane is required to cause a decrease in E scis to the same level, and for hexane addition levels above 70 mM a disruption in the plateau modulus indicates the disruption of the rodlike structure. The correspondence between the effect of temperature and the effect of solvent addition allows the development of "solvent/temperature" superposition rules to predict the rheology of these viscoelastic fluids at elevated temperatures.

Original languageEnglish (US)
Pages (from-to)8970-8974
Number of pages5
JournalLangmuir
Volume20
Issue number21
DOIs
StatePublished - Oct 12 2004

All Science Journal Classification (ASJC) codes

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

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