Structural characterization of amphiphilic homopolymer micelles using light scattering, SANS, and Cryo-TEM

Joseph P. Patterson, Elizabeth G. Kelley, Ryan P. Murphy, Adam O. Moughton, Mathew P. Robin, Annhelen Lu, Olivier Colombani, Christophe Chassenieux, David Cheung, Millicent O. Sullivan, Thomas H. Epps, Rachel K. O’Reilly

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22 Citations (Scopus)

Abstract

We report the aqueous solution self-assembly of a series of poly(N-isopropylacrylamide) (PNIPAM) polymers end-functionalized with a hydrophobic sulfur–carbon–sulfur (SCS) pincer ligand. Although the hydrophobic ligand accounted for <5 wt % of the overall homopolymer mass, the polymers self-assembled into well-defined spherical micelles in aqueous solution, and these micelles are potential precursors to solution-assembled nanoreactors for small molecule catalysis applications. The micelle structural details were investigated using light scattering, cryogenic transmission electron microscopy (cryo-TEM), and small angle neutron scattering (SANS). Radial density profiles extracted from the cryo-TEM micrographs suggested that the PNIPAM chains formed a diffuse corona with a radially decreasing corona density profile and provided valuable a priori information about the micelle structure for SANS data modeling. SANS analysis indicated a similar profile in which the corona surrounded a small hydrophobic core containing the pincer ligand. The similarity between the SANS and cryo-TEM results demonstrated that detailed information about the micelle density profile can be obtained directly from cryo-TEM and highlighted the complementary use of scattering and cryo-TEM in the structural characterization of solution assemblies, such as the SCS pincer-functionalized homopolymers described here.
Original languageEnglish
Pages (from-to)6319–6325
Number of pages7
JournalMacromolecules
Volume46
Issue number15
Early online date18 Jul 2013
DOIs
Publication statusPublished - 2013

Keywords

  • structural characterization
  • amphiphilic homopolymer micelles
  • light scattering
  • SANS
  • cryo-TEM

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    Patterson, J. P., Kelley, E. G., Murphy, R. P., Moughton, A. O., Robin, M. P., Lu, A., Colombani, O., Chassenieux, C., Cheung, D., Sullivan, M. O., Epps, T. H., & O’Reilly , R. K. (2013). Structural characterization of amphiphilic homopolymer micelles using light scattering, SANS, and Cryo-TEM. Macromolecules, 46(15), 6319–6325. https://doi.org/10.1021/ma4007544