Block copolymer vesicle permeability measured by osmotic swelling and shrinking

Langmuir. 2011 Apr 19;27(8):4884-90. doi: 10.1021/la105045m. Epub 2011 Mar 15.

Abstract

Vesicle response to osmotic shock provides insight into membrane permeability, a highly relevant value for applications ranging from nanoreactor experimentation to drug delivery. The osmotic shock approach has been employed extensively to elucidate the properties of phospholipid vesicles (liposomes) and of varieties of polymer vesicles (polymersomes). This study seeks to compare the membrane response for two varieties of polymersomes, a comb-type siloxane surfactant, poly(dimethylsiloxane)-g-poly(ethylene oxide) (PDMS-g-PEO), and a diblock copolymer, polybutadiene-b-poly(ethylene oxide) (PBut-b-PEO). Despite similar molecular weights and the same hydrophilic block (PEO), the two copolymers possess different hydrophobic blocks (PBut and PDMS) and corresponding glass transition temperatures (-31 and -123 °C, respectively). Dramatic variations in membrane response are observed during exposure to osmotic pressure differences, and values for polymer membrane permeability to water are extracted. We propose an explanation for the observed phenomena based on the respective properties of the PBut-b-PEO and PDMS-g-PEO membranes in terms of cohesion, thickness, and fluidity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Membrane Permeability
  • Hydrophobic and Hydrophilic Interactions
  • Models, Biological*
  • Osmosis*
  • Osmotic Pressure
  • Permeability
  • Polymers / chemistry*
  • Transition Temperature
  • Water / chemistry*

Substances

  • Polymers
  • Water