CO2‑Reactive Ionic Liquid Surfactants for the Control of Colloidal Morphology

• Published in: Langmuir Vol. 33; no. 31; pp. 7633 - 7641
• Main Authors: Brown, Paul, Sresht, Vishnu, Eral, Burak H, Fiore, Andrew, de la Fuente-Núñez, César, O’Mahony, Marcus, Mendes, Gabriel P, Heller, William T, Doyle, Patrick S, Blankschtein, Daniel, Hatton, T. Alan
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 08.08.2017
• Subjects: bromides; carbon dioxide; CO2-responsive; DNA; DNA compaction; droplets; electrical conductivity; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Ionic Liquids; MD simulations; molecular dynamics; neutrons; nitrogen; proline; Surfactants; thermogravimetry
• ISSN: 0743-7463; 1520-5827; 1520-5827
• DOI: 10.1021/acs.langmuir.7b00679

This article reports on a new class of stimuli-responsive surfactant generated from commercially available amphiphiles such as do­decyl­tri­methyl­am­mmonium bromide (DTAB) by substitution of the halide counterion with counterions such as 2-cyano­pyrrolide, 1,2,3-tri­azolide, and L-proline that complex reversibly with CO2. Through a combination of small-angle neutron scattering (SANS), electrical conductivity measurements, thermal gravimetric analysis, and molecular dynamics simulations, we show how small changes in charge reorganization and counterion shape and size induced by complexation with CO2 allow for fine-tunability of surfactant properties. We then use these findings to demonstrate a range of potential practical uses, from manipulating microemulsion droplet morphology to controlling micellar and vesicular aggregation. In particular, we focus on the binding of these surfactants to DNA and the reversible compaction of surfactant–DNA complexes upon alternate bubbling of the solution with CO2 and N2.