title: Size change of the wormlike micelles of pentaoxyethylene, hexaoxyethylene, and heptaoxyethylene dodecyl ethers with uptake of n-dodecane.
abstract: Wormlike micelles of the surfactant penta-, hexa-, and heptaoxyethylene dodecyl ethers C12 E5, C12 E6, and C12 E7 were characterized by static light scattering (SLS) and dynamic light scattering (DLS) experiments to examine effects of uptake of n-dodecane on the micellar characteristics. The SLS results have been successfully analyzed by the light scattering theory for micelle solutions to yield the molar mass Mw(c) as a function of concentration c along with the cross-sectional diameter d of the micelle. The apparent hydrodynamic radius RH,app(c) determined by DLS as a function of c has also been successfully analyzed by the fuzzy cylinder theory which (-1). It has been found that the micellar length Lw increases with increasing surfactant mass concentration c and the values of d and lambda(-1) increase with increasing n-dodecane content wd, as in the case of various CiEj micelles containing n-alcohol. On the other hand, the values of Mw, Lw, and RH,app for all the micelles examined decrease with increasing wd contrary to the micelles containing n-alcohol. This finding may be attributed to the fact that the addition of n-dodecane into the micelles weakens hydrophilic interactions among polyoxyethylene chains of the surfactant molecules and water, making the micelles unstable, and then leading them to collapse into smaller micelles.
authors: Department of Chemistry, Nara Women's University, Nara 630-8506, Japan.
authors: Maiko
authors: M
authors: Miyake
authors: Ayako
authors: A
authors: Asano
authors: Yoshiyuki
authors: Y
authors: Einaga
mesh_terms: D000473:Alkanes / Q000737:chemistry*; D004987:Ethers / Q000737:chemistry*; D008027:Light; D008823:Micelles; D010316:Particle Size; D044367:Phase Transition; D011092:Polyethylene Glycols / Q000737:chemistry*; D012542:Scattering, Radiation; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D000473:Alkanes; D004987:Ethers; D008823:Micelles; D013501:Surface-Active Agents; C529615:heptaoxyethylene dodecyl ether; C529616:pentaoxyethylene dodecyl ether; C007548:n-dodecane; C028808:hexaoxyethylene dodecyl ether; D011092:Polyethylene Glycols