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Investigation of the properties of decaoxyethylene n ‐dodecyl ether, C 12 E 10 , in the aqueous sugar‐rich region
Author(s) -
Sharma K. Shivaji,
Rakshit Animesh Kumar
Publication year - 2004
Publication title -
journal of surfactants and detergents
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.349
H-Index - 48
eISSN - 1558-9293
pISSN - 1097-3958
DOI - 10.1007/s11743-004-0316-8
Subject(s) - chemistry , micelle , aqueous solution , aggregation number , enthalpy , heat capacity , small angle neutron scattering , critical micelle concentration , analytical chemistry (journal) , thermodynamics , neutron scattering , organic chemistry , scattering , physics , optics
Interfacial, thermodynamic, and morphological properties of decaoxyethylene n ‐dodecylether [CH 3 (CH 2 ) 11 (OCH 2 CH 2 ) 10 OH](C 12 E 10 ) in aqueous solution were analyzed by tensiometric, viscometric, proton nuclear magnetic resonance (NMR), and small‐angle neutron scattering (SANS) techniques. Dynamic and structural aspects at different temperatures in the absence and presence of sugars at different concentrations were measured. Critical micelle concentrations (CMC) were determined by surface tension measurements in the presence of ribose, glucose, and sucrose. The heat capacity (Δ C p.m. ), transfer enthalpy (Δ H m.tr. ), transfer heat capacities (Δ C p.m.tr. ), micellization constant ( K m ), Setchenow constant ( K S N ), and partition coefficient ( q ) were determined and discussed as an extension of the usual thermodynamic quantities of micellization and adsorption at the air‐water interface. An enthalpy‐entropy compensation effect was observed with an isostructural temperature ( T c ) of about 310 K for both micellization and interfacial adsorption. SANS measurements were taken to elucidate structural information, viz. , aggregation number ( N agg ), shape, size, and number density ( N m ) on C 12 E 10 micelles in D 2 O at different concentrations of sugars (0.05, 0.02, 0.3, and 0.5 M) and temperatures (30, 45, and 60°C). Intrinsic viscosity gave the hydrated micellar volume (V h ), volume of the hydrocarbon core ( V c ), and volume of the palisade layer of the oxyethylene (OE) unit ( V OE ). SANS, as well as rheological data, supported the formation of nonspherical micelles with or without sugars. By SANS, we also observed that at the studied temperature intervals, oblate ellipsoid micelles changed into prolate ellipsoids and the number density of micelles decreased with an increase in temperature both in the presence and in the absence of sugars and also on increasing the concentration of sugars. Proton NMR showed a change in chemical shift of the OE group of micelles above the CMC. We also studied the phase separation of C 12 E 10 by sugars in cloud point measurements.