Phase Behavior of a Lipid/Polymer-Lipid Mixture in Aqueous Medium

Kalina Hristova, David Needham

Research output: Contribution to journalArticle

Abstract

The phase behavior of a mixture of bilayer forming lipids and polymer-lipids (lipids with covalently attached polymer to their hydrophilic moieties) in excess water is studied theoretically. The mixture is predicted to exhibit complex phase behavior for polymer molecular weights 2000 and 5000, depending on the concentration (fraction) of polymer-lipids in the lipid mixture. The bilayer is characterized by a maximal concentration nMt (saturation limit) of polymer-lipids that it can incorporate, as determined by its material properties (elastic modulus of area expansion and critical area expansion). At a different concentration ntr, which we call the thermodynamics crossover, micelle formation becomes energetically favorable over bilayer formation. We show that for DSPC and SOPC bilayers ntr < nsat. Increase of the polymer-lipid concentration above ntr leads to a gradual transition from a bilayer to a micellar phase; bilayers and micelles can coexist. In the transition region the polymer-lipid concentration is higher in the micellar phase than in the coexisting bilayer.

Original languageEnglish (US)
Pages (from-to)991-1002
Number of pages12
JournalMacromolecules
Volume28
Issue number4
DOIs
StatePublished - Jul 1 1995
Externally publishedYes

ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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