TY - JOUR
T1 - Structure effect on nonideal mixing of alkyl methyl sulfoxide and alkyldimethylphosphine oxide in adsorbed film and micelle
AU - Iyota, Hidemi
AU - Todoroki, Natsuko
AU - Ikeda, Norihiro
AU - Motomura, Kinsi
AU - Ohta, Akio
AU - Aratono, Makoto
PY - 1999/8/1
Y1 - 1999/8/1
N2 - The surface tension of aqueous solutions of the octylmethylsulfoxide (OMS)-decyldimethylphosphine oxide (DePO) and decylmethylsulfoxide (DeMS)- octyldimethylphosphine oxide (OPO) mixtures was measured as a function of the total molality of the surfactants and the composition in the surfactants. Compositions in the adsorbed film and micelle were thermodynamically evaluated from the total molality vs composition and the critical micelle concentration (CMC) vs composition curves, respectively. The phase diagrams of adsorption and micelle formation were drawn and compared with those of the DeMS-DePO mixture previously studied. A large gap in composition was observed between the adsorbed film and the micelle coexisting at the CMC and ascribed to the differences in geometric structure between them and the constituent molecules. Negative deviation from ideal mixings in adsorbed film and micelle was observed for the OMS-DePO mixture, whereas a positive one was observed for the DeMS-OPO. The structure effect on the nonideal mixings was clarified by using the excess thermodynamic functions of adsorption and micelle formation calculated from the activity coefficients in the adsorbed film and micelle.
AB - The surface tension of aqueous solutions of the octylmethylsulfoxide (OMS)-decyldimethylphosphine oxide (DePO) and decylmethylsulfoxide (DeMS)- octyldimethylphosphine oxide (OPO) mixtures was measured as a function of the total molality of the surfactants and the composition in the surfactants. Compositions in the adsorbed film and micelle were thermodynamically evaluated from the total molality vs composition and the critical micelle concentration (CMC) vs composition curves, respectively. The phase diagrams of adsorption and micelle formation were drawn and compared with those of the DeMS-DePO mixture previously studied. A large gap in composition was observed between the adsorbed film and the micelle coexisting at the CMC and ascribed to the differences in geometric structure between them and the constituent molecules. Negative deviation from ideal mixings in adsorbed film and micelle was observed for the OMS-DePO mixture, whereas a positive one was observed for the DeMS-OPO. The structure effect on the nonideal mixings was clarified by using the excess thermodynamic functions of adsorption and micelle formation calculated from the activity coefficients in the adsorbed film and micelle.
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U2 - 10.1006/jcis.1999.6274
DO - 10.1006/jcis.1999.6274
M3 - Article
AN - SCOPUS:0033179732
SN - 0021-9797
VL - 216
SP - 41
EP - 49
JO - Journal of Colloid and Interface Science
JF - Journal of Colloid and Interface Science
IS - 1
ER -