Structural Characterization of Amphiphilic Homopolymer Micelles Using Light Scattering, SANS, and Cryo-TEM

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• 作者：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 ; III ; Rachel K. O鈥橰eilly
• 刊名：Macromolecules
• 出版年：2013
• 出版时间：August 13, 2013
• 年：2013
• 卷：46
• 期：15
• 页码：6319-6325
• 全文大小：372K
• 年卷期：v.46,no.15(August 13, 2013)
• ISSN：1520-5835

文摘

We report the aqueous solution self-assembly of a series of poly(N-isopropylacrylamide) (PNIPAM) polymers end-functionalized with a hydrophobic sulfur鈥揷arbon鈥搒ulfur (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.