Micellar Properties and Critical Opalescence of Dimethyalkylphosphine Oxide Solutions

Abstract

Phase diagrams and light-scattering measurements of a homologous series of dimethylalkylphosphine oxides are used to determine the micellar molecular weights and their relation to consolute phase boundaries in these systems. The temperature dependence of micellar molecular weights is discussed with regard to both light-scattering and solution theory, and it is concluded that, in systems which show consolute boundaries, the lightscattering behavior can be qualitatively explained on the basis of existing theory without invoking any large temperature or concentration dependence of micellar molecular weight. The observed light-scattering behavior can easily be accounted for by the nonideality of a micellar solution and the temperature dependence of micellar-water interactions. Lightscattering measurements at the critical concentration for phase separat,ion of the dimethyldodecylphosphine oxide-water system have also been made and show that, critical opalescence is observed in this system. These results are discussed in the light of existing theoretical treatments of this phenomenon, and the experimental results are shown to agree qualitatively with the theory.

Neutron scattering studies on micelles of dodecylhexaoxyethylene glycol monoether

“…One of the early light scattering examinations of dodecylhexaoxyethylene glycol monoether (C12E6) suggested the formation of micelles of micellar weight in the region 60,000-84,600 at ambient temperatures and indicated that there was a variation with temperature; it was also clear that under these conditions the micelles were non-spherical [1]. Subsequent light scattering studies on C12E6 and other homogeneous polyoxyethylene glycol monoethers reported a pronounced variation of micellar weight with temperature [2,3] and similar results were obtained with alkyldimethyl phosphine oxides [4] and alkylsulphinyl alkanols [5]. These authors concluded that interpretation of the light scattering results was complicated by the non-ideality of the system.…”

Purification, Surface Tensions, and Miscibility Gaps of Alkyldimethyl and Alkyldiethylphosphine Oxides

“…8. Again, it is the less polar head group of C 12 DEPO which is responsible for its lower water solubility, which influences both the cmc [21] a Note that the coordinates of the lower critical consolution point are not given in [2] but were estimated from the respective miscibility gaps. Due to the low number of data provided in [2] the c c could not or only approximately be determined and the miscibility gap.…”

“…For example, extensive surface tension [7][8][9][10][11][12][13] and surface rheology [14][15][16][17][18][19][20] studies have been carried out with a focus on the properties of C 12 DMPO. In addition, the binary water-surfactant phase diagrams of C 8 DMPO [21], C 10 DMPO [21], C 12 DMPO [2,3,21], and C 14 DMPO [2,3] were studied, and the formation of microemulsions with C 10 , C 12 , and C 14 DMPO was investigated [3]. Finally, there are studies on the interactions between C 12 DMPO surfactant layers adsorbed on hydrophobized mica [22] and on the adsorption of C 10 DMPO and C 12 DMPO on silica [23,24].…”

A new micellar aqueous two-phase partitioning system (ATPS) for the separation of proteins

“…The aqueous phase diagrams for several members of the APO family of compounds have been determined over a broad concentration range [13]. The lower consulate temperature (LCT) for 10% solutions of APO10 and APO12 was approximately 125 and 40 • C, respectively.…”

“…The phase separation temperature was modeled using regular solution theory, and it is related to the molecular weight of the micelles and mixed micelles [15]. The composition of the two liquid phases that result from heating aqueous solutions of several aqueous APO and APO/PL mixtures above the lower critical solution temperature (LCST), or cloud point, has been determined [13,16], and it is possible that the liquid-liquid phases that are formed by these mixtures have potential use for protein separations, particularly membrane proteins which require non-conventional methods [17].…”