title: The ability of single-chain surfactants to emulsify an aqueous-based liquid crystal oscillates with odd-even parity of alkyl-chain length.
abstract: The physical properties of many organic molecules often oscillate when the number of carbons in their aliphatic chains changes from odd to even. This odd-even effect for single-chain surfactants in solution is rarely observed. Here, we report the ability of single-chain surfactants to emulsify a class of non-amphiphilic organic salts, disodium cromoglycate (5'DSCG) oscillates as a function of the odd or even number of the aliphatic carbons. This system provides a water-in-oil-in-water emulsion, in which aqueous droplets of 5'DSCG in liquid crystal phases are coated with single-chain surfactants in a bulk carrying aqueous solution. For both surfactants of [Formula: see text] and CH3(CH2)nCOO(-)Na(+), the ability to emulsify 5'DSCG molecules in water is stronger for surfactants with an odd number of sp(3)-hybridized carbon atoms in the aliphatic chains than those with an even number. This observed odd-even effect is consistent with the notion that conventional micelles possess a core of randomly arranged surfactant hydrocarbon tails. However, this water-in-oil-in-water resembles a vesicle system in which the surfactants assemble in a highly ordered structure that separates two aqueous systems. These new self-assembled phases have potential application in the formulation and design of new organic soft materials.
authors.affiliation: Department of Chemistry, Department of Biomedical and Chemical Engineering, Syracuse University, Syracuse, NY 13244-4100, United States.
authors.forename: Nisha
authors.initials: N
authors.lastname: Varghese
authors.forename: Gauri S
authors.initials: GS
authors.lastname: Shetye
authors.forename: Sijie
authors.initials: S
authors.lastname: Yang
authors.forename: Stephan
authors.initials: S
authors.lastname: Wilkens
authors.forename: Robert P
authors.initials: RP
authors.lastname: Smith
authors.forename: Yan-Yeung
authors.initials: YY
authors.lastname: Luk
mesh_terms: D003460:Crystallization; D004655:Emulsions; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water / Q000737:chemistry
chemical_list: D004655:Emulsions; D013501:Surface-Active Agents; D014867:Water
keywords: Chromonic liquid crystal; Disodium cromoglycate (5′DSCG); Odd–even effect; Single-chain surfactants; Water-in-oil–water emulsion