Reversibly formed bilayer vesicles: Energetics and polydispersity

M. Bergstöm

    Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review


    Model calculations based on the multiple equilibrium approach indicate that the spontaneous formation of geometrically closed bilayer vesicles is geared primarily by the bilayer tension which in turn is largely determined by the work of bending the bilayer into a spherical vesicle. and a statistical-mechanical factor that accounts for the fluctuations in composition, chain packing density and shape. We demonstrate that the free energy required to form a spherical vesicle is made up of two main contributions: the (size-independent) work of bending the constituent monolayers and the work of stretching the bilayer that is determined by the planar bilayer tension. A previously undiscovered contribution to the work of bending a vesicle bilayer, originating from geometrical packing constraints, is presented. On this basis we obtain vesicle size distributions with maxima located at radii several orders of magnitude larger than where the local free energy minima of the equilibrium vesicle actually occur. Moreover, according to our analysis, the relative width of a vesicle size distribution, sigma(R)/R-max, is generally at full equilibrium equal to 0.283, independently of the energetic vesicle parameters. Our calculations of the bending work of mixed SDS/dodecanol bilayers predict vesicles with R-max in the range of 0.1-10 mu m and for mixed anionic/cationic bilayers we obtain small unilamellar vesicles with R-max < 1000 Angstrom when one of the surfactants is in excess, in good qualitative agreement with recent experimental findings.
    Original languageEnglish
    Title of host publicationTrends in Colloid and Interface Science XI
    Publication date1997
    ISBN (Print)3-7985-1086-5, 978-3-7985-1086-9
    ISBN (Electronic)978-3-7985-1660-1
    Publication statusPublished - 1997
    Event10th Annual meeting in the European Colloid and Interface Society - Turku, Finland
    Duration: 2 Sep 19966 Sep 1996
    Conference number: 10


    Conference10th Annual meeting in the European Colloid and Interface Society
    SeriesProgress in Colloid and Polymer Science


    • Surfactant aggregation
    • Bilayer membrane
    • Spontaneous vesiculation
    • Curvature elasticity
    • Size distribution


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