title: Chaotropic-anion-induced supramolecular self-assembly of ionic polymeric micelles.
abstract: Traditional micelle self-assembly is driven by the association of hydrophobic segments of amphiphilic molecules forming distinctive core-shell nanostructures in water. Here we report a surprising chaotropic-anion-induced micellization of cationic ammonium-containing block copolymers. The resulting micelle nanoparticle consists of a large number of ion pairs (≈60,000) in each hydrophobic core. Unlike chaotropic anions (e.g. ClO4(-)), kosmotropic anions (e.g. SO4(2-)) were not able to induce micelle formation. A positive cooperativity was observed during micellization, for which only a three-fold increase in ClO4(-) concentration was necessary for micelle formation, similar to our previously reported ultra-pH-responsive behavior. This unique ion-pair-containing micelle provides a useful model system to study the complex interplay of noncovalent interactions (e.g. electrostatic, van der Waals, and hydrophobic forces) during micelle self-assembly.
authors.affiliation: Department of Pharmacology, Harold C. Simmons Comprehensive Cancer Center, UT Southwestern Medical Center at Dallas, 5323 Harry Hines Blvd., Dallas, TX 75390 (USA).
authors.forename: Yang
authors.initials: Y
authors.lastname: Li
authors.forename: Yiguang
authors.initials: Y
authors.lastname: Wang
authors.forename: Gang
authors.initials: G
authors.lastname: Huang
authors.forename: Xinpeng
authors.initials: X
authors.lastname: Ma
authors.forename: Kejin
authors.initials: K
authors.lastname: Zhou
authors.forename: Jinming
authors.initials: J
authors.lastname: Gao
mesh_terms: D000838:Anions / Q000737:chemistry*; D031541:Fluorescence Resonance Energy Transfer; D008823:Micelles; D046529:Microscopy, Electron, Transmission; D011108:Polymers / Q000737:chemistry*
chemical_list: D000838:Anions; D008823:Micelles; D011108:Polymers
keywords: anti-Hofmeister effect; block copolymers; ion pairs; micelles; self-assembly