Effect of Solvent Selectivity on Chain Exchange Kinetics in Block Copolymer Micelles

ORAL

Abstract

Block copolymer (BCP) micelles in selective solvents are useful for a variety of applications, such as nanolithography, drug delivery, and viscosity modification. The solvent quality is an important factor for both thermodynamics and dynamics of BCP micelles. Previous work revealed the effect of solvent selectivity on thermodynamic properties of BCP micelles formed by poly(styrene-b-ethylene-alt-propylene) (PS-PEP) diblock copolymers in mixed solvents of squalane and 1-phenyldodecane. The systematic change of solvent composition tunes the interfacial tension between the core and corona-solvent matrix, embodied in the Flory-Huggins interaction parameter χ. This should also affect the kinetics of chain exchange between micelles. This presentation will describe the consequences of varying the solvent composition on the rate of chain exchange using time-resolved small-angle neutron scattering (TR-SANS). An independent method, static light scattering (SLS), was performed to estimate χ between the core block and the solvent as a function of solvent composition and temperature. Based on TR-SANS and SLS results, the dependence of the chain exchange rate on χ can be quantified.

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Presenters

  • En Wang

    University of Minnesota

Authors

  • En Wang

    University of Minnesota

  • Dan Zhao

    University of Minnesota

  • Timothy Lodge

    University of Minnesota, Department of Chemistry, University of Minnesota, Twin Cities, University of Minnesota - Twin Cities, Chemistry, University of Minnesota, Department of Chemistry, University of Minnesota

  • Frank Bates

    Department of Chemical Engineering & Materials Science, University of Minnesota, Chemical Engineering and Materials Science, University of Minnesota, Department of Chemical Engineering and Materials Science, University of Minnesota, Twin Cities, University of Minnesota, University of Minnesota - Twin Cities, Chemical Engineering and Material Science, University of Minnesota, Department of Chemical Engineering and Materials Science, University of Minnesota