Size change of the wormlike micelles of pentaoxyethylene, hexaoxyethylene, and heptaoxyethylene dodecyl ethers with uptake of n-dodecane.
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.
Miyake
Maiko
M
Department of Chemistry, Nara Women's University, Nara 630-8506, Japan.
Asano
Ayako
A
Einaga
Yoshiyuki
Y
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*
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