J. Phys. Chem. 1980, 84, 1567-1570
are greatfully acknowledged. References and Notes (1) Vijayan, S.;Ramachandran,C.; Shah, D. O., J. Am. Oil. Chem. SOC. In press. (2) Vijayan, S.;Ramachandran, C.; Shah, D. O., J. Am. Oil Chem. SOC. In press. (3) Hsieh, W. C.; Shah, D. 0. SPE 6600 Paper presented at International Symposium of Oil Field and Geothermal Chemists of the Society of Petroleum Engineers, AIME, LaJolla, CA, June 27-28, 1977. (4) Butler, K. W.; Tattrie, N. H.; Smith, I. C P. Biochim. Biophys. Acta 1974, 363, 351. (5) Hsla, J. C.; Schneider, H.; Smith, I. C. P. Can. J . Biochem. 1971, 49,614. (6) Hubbell, Vi. L.; McConnell, H. M. J. Am. Chem. SOC.1971, 93, 314. (7) Stone, T. J.; Buckman, T.; Nordio, P. L.; McConnell, H. M. Proc. Natl. Acad. Sci. U . S . A . 1965, 54, 1010. (8) McConnell, H. M.; McFarland, B. G. Q. Rev. Biophys. 1970, 3 , 91.
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(9) Schreier-Muccillo, S.;Marsh, D.; Dugas, H.; Schneider, H.; Smith, I. C. P. Chem. Phys. Lipids 1973, 10, 11. (10) Seelig, J.; Hasselbach, W. Eur. J . Biochem. 1971, 21, 17. (1 1) Smith, I. C. P. in "Biological Applications of Electron Spin Resonance Spectroscopy", Bolton, J. R.; Borg D.; Schwartz, H., Ed.; Wiley-lnterscience: New York, 1972; p 483. 1121 Seelia. J. J . Am. Chem. SOC.1970. 92. 3881. (13j Sans% A.; Ptak, M.; Rigaud, J. L.; &ry-Bobo, C. M. Chem. Phys. Lipids 1976, 17, 435. (14) Shiga, T.; Suda, T.; Maeda, N. Biochim. Biophys. Acta 1977, 466, 23 1. (15) Ernandes, J. R.; Chaimovich, H. 0.; Schreier, S. Chem. Phys. Lipids 1977, 18, 304. (16) Paleos, C. M.; Dais, P. J. Chem. Soc., Chem. Commun. 1977, 345. (17) Kornberg, R. D.; McConnell, H, M. Biochemistry 1971, 10, 1111. (18) Keith, A. D.; Melhorn, R. J.; Freeman, N. K.; Nichols, A. V. Chem. Phvs. Lioids 1973. 10. 223. (19) Sihreiei-Muccillo,'S.; Marsh, D.; Smith, I. C. P. Arch. Biochem. Biophys. 1976, 172, 1.
Phase DLagrarns of Oxyalkylates. 2 G. M. Bradley and K. J. Lissant" Petroiite Corporation, St. Louis, Missouri 63 119 (Received October 1, 1979) PubYication costs assisted by Petroilte Corporation, Tretoiite Division
Studies on the system Shellflex 131-water-oxyethylated 1-decanol have been extended to monodisperse CloH21-0-(C2H40)41-Iand to mixtures of oxyethylated 1-decanol compounds having average chain lengths of four oxyethylene units. Ternary diagrams are given at 10, 25, 40 and 60 "C, as well as some data on temperature-composition planes. Surfactants with monodisperse and broad, monomodal, distributions exhibited similar behavior, forming micellar and liquid crystal phases over wide composition ranges. The surfactant with a bimodal distributioin formed practically no micellar or liquid crystal phases. In this case the type of oxyethylene distribution was a factor in the phase behavior of the surfactants. Introduction Most phase diagram studies of water-organic solventsurface-active compound systems have been conducted on pure ionic compounds and pure hydrocarbons. A few systems inccirporating carefully prepared or purified nonionic materials have been studied. Although megatons of surfactants are made and used each year very few of these products are pure compounds. We have been conducting studies to determine whether the techniques employed with homogeneous surfactants can be applied to commercial formulations. In a previous paper we investigated the system water-surfactant-hydrocarbon where the hydrocarbon was a commercial aliphatic solvent and the surfactant was a material prepared by reacting ethylene oxide with 1-decanol by use of commercial methods. Phase diagrams were presented to show the results. In a strict sense triangular diagrams cannot be used to depict these systems since the surfactant is made up of a spectrum of closely related compounds. Tie lines cannot be drawn on a triangular diagram since the surfactant itself may disproportionate. We were able to show that reproducible results could be obtained and that useful information could be displayed in triangular diagrams. In fact, the behavior of the "heterogeneous" surfactants did not depart drastically from that expected of closely related homogeneous materials. Each of these commercial surfactants had a typical distribution of individual species around an average value. This paper seeks to show what happens where atypical distributions are investigated. Three materials were used in this study, each with an average of four oxyethylene units per decane One had a monodisperse oxyethylene 0022-3654/80/2084-1567$0 1.OO/O
distribution, the second had a broad monomodal distribution, and the third had a bimodel distribution. Experimental Section -The homogeneous surfactant was prepared by the method of Gingras and Bailey2 from 1-chlorodecane and tetraethylene glycol. Eastman tetraethylene glycol (1L), used as received but checked by gas chromatography, was placed in a resin kettle and heated, stirred, and purged with N2 to remove any water. Heating was stopped and 25 g of Na was added in small pieces over a 5-h period. The mixture was allowed to react without heating, but with stirring and N2 purging, for 16 h more. 1-Chlorodecane (195/g, MCB, used as received), such that tetraethylene glycol was in 5/1 mole excess, was added dropwise over a 1.5-h period after the pot was heated to 130 "C. The temperature fluctuated between 120 and 150 "C over the entire 3-h reaction period. Attempts to determine the point of completion by pH paper were unsuccessful, Finally the reaction mixture was filtered to remove salt. The filtrate was distilled under vacuum. A few milliliters of 1-decenewere collected in the trap. Excess tetraethylene glycol distilled at 170 "C with 1 mm pressure. The distillation was stopped at 190 "C (CloE4has a boiling point of 195 "C at 1 mm) and the residue, 200 mL of a black liquid, was collected. The residue was dissolved in 800 mL of CHC13and the solution was used as the solvent to slurry pack a column (52 cm high X 5.2 cm i.d.) of silica (Davison, grade 950, 80-200 mesh). The chloroform solution was eluted with 1.5 L of 19/1 ether/methanol in two stages. The final eluent was 2 / 1 ether/methanol. After evaporation, the 0 1980 American Chemical Society
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chloroform residue (A) was 100 mL, the first 19/1 ether methanol 40 mL (B) and the second 40 mL (6). The 2/1 ether/methanol contained only 5 mL of residue, but most of the colored material. By GC analysis, A was found to contajn 15% of a material (presumablythe diether) eluting after the main peak, B was pure C10E4,and C contained 0.1% of the diether. B and C were combined and designatecl S-30. For NMR analysis, 5% solutions were made in CD& or CS2and NMR spectra were recorded on a Perkin-Elmer R-32. Peaks due to oxyethylene protons in the range 3.0-4.2 ppm and peaks due to aliphatic protons in the range 0.6-1.8 ppm were integrated and the number of oxyethylene units per decane unit, that is, the number average oxyethylene chain length, was calculated to be 4.0. The hydroxyl proton gave rise to a broad peak at 2.5 ppm and was excluded from the analysis. The accuracy of the analysis was -2%. The refractive index was 1.4495 at 25 "C, compared with the literature value of 1.4494.3 A broad distribution surfactant blend was prepared by first removing l-decanol under vacuum distillation from some of the surfactants reported in a previous paper. To one with average chain length of 3.8 oxyethyleneunits was then added 27% of one with average chain length 4.7 oxyethylene units, leading to a mixed surfactant with average chain length by NMR analysis of 4.0 and designated S-75. A bimodal surfactant blend was prepared by mixing two fractions, each separated from polydisperse materials reported in the previous paper.' For the short chain fraction, a vacuum distillation cut was taken such that 1 , 2 , and 3 mol adducts were collected. Care was taken to exclude 1-decanol. The NMR average chain length was 1.9 oxyethylene units. The long chain length fraction was prepared by extracting a broad distribution surfactant with hexane. The results was a solid, melting at -40 "C, whose average chain lenglh was 7.3 oxyethylene units. A mixture of 40% of the long chain and 60% of the short chain material had average chain length of 4.0 and was designated S-68. Gas chromatography was tried to characterize the distributions, but the instrument failed to detect long chain length components adequately; number-average chain lengths calculated from GC data were lower than from NMR data and the deviation was worse the longer the chain. Refractive indices measured at 40 "C in an Abbe refractometer were 1.4438 for S-30, 1.4440 for S-76, and 1.4442 for S-68. As expected from the contribution of weight and higher averages to the refractive index, the broader the distribution the higher the refractive index. The hydrocarbon used was Shellflex 131, a commercial aliphatic solvent from Shell Oil Co., which is low in aromaticity with over 92% aliphatic hydrocarbons and an estimated average molecular weight of 270. Detailed characterization data are available from Shell Oil Co. The phase diagrams were determined by placing the required amounts of each component in a 10-mL test tube and mixing and equilibrating at each of four temperatures (10, 25, 40, and 60 "C). Once equilibrated, the samples were tested for conductivity by using a two-wire probe in an ASTM D244-69 particle charge tester. They were examined between polarizing filters for anisotropy and observations were made on clarity, number of phases, and rate of separation of the phases. On these bases the diagrams were found to contain five regions. Type one is a single phase, clear, isotropic, and nonconductive or slightly conductive region. T y p e two is a cloudly to opaque region containing at least two phases. In a previous paper1 we made a dis-
Bradley and Lissant
Figure 1. Phase diagrams of S-30 at various temperatures: (A) 10 OC, (B) 25 "C,(C) 40 OC,and (D) 60 "C;(W) water; (H) Shellflex-131; and (S)surfactant. The regions are numbered according to type: (1) clear, isotropic, oil-rich; (2) two-phase; (3)clear or hazy, anisotropic, water-rich; (4) solid phase; (5) clear water-rich phase.
tinction between mixtures which separated quickly and cleanly and those mixtures which formed fairly stable dispersions (type four in the previous paper). Type three is anisotropic and clear or hazy. Type four is a solid phase which occurs at high surfactant concentrations below the melting point of the surfactant. Type fiue is a single phase, clear, isotropic, and conductive region. As before, the quantities of the components and the coded results were entered into a computer file; a program calculated and plotted the phase diagrams. Tabulated raw data are available on request. Besides the determinations run at the four temperatures, "slices" through the temperature axis were also made. In these determinations each mixture was placed in a 1 oz bottle with a thermometer inserted through a rubber stopper. The mixture was heated and cooled within the range 10-60 "C while observations on phase changes were made.
Discussion Because both the hydrocarbon and the surfactant are not pure identities in the case of S-75 and S-68 it is not strictly proper to represent results on a ternary diagram. Also, since the hydrocarbon and the surfactant species may disproportionate between phases, tie lines cannot be drawn. In spite of these limitations, ternary diagrams are still a useful technique for depicting results. Figure 1 shows the ternary diagrams at the four temperatures for the monodisperse material S-30. A large clear isotrqpic region, presumably inverse micelles, occurs along the oil-surfactant side of the diagram at each temperature. At 10 " C another clear isotropic region, presumably normal micelles, occurs along the water-surfactant side, as well as an an anisotropic region. As the temperature increases, the regions become smaller, except that at 40 "C the inverse micellar region extends toward the water corner. By 60 " C only the inverse micellar region remains. Figure 2 shows comparable data for the normal distribution material S-75. The results, while not identical, are quite similar. The same regions can be identified, but persist at somewhat higher temperatures. Figure 3 shows the equivalent results for the bimodal material S-68. The results here are quite different. There is a much smaller inverse micellar region and the other regions are absent or greatly reduced. Actually the situation is much more complicated than these few figures would lead one to believe. In the process
The Journal of Physical Chemistry, Vol. 84, No. 12, 1980
Phase Diagrams of Ox,yalkylates A
SURFACTANT
E
v Lo
H/SA=II/S
W/SA=II/9
% MATER
%OIL
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S-30 W/SA=9/11
W/SA=4
W/SA=9
W
W
E68 LP
1 E 11 48
29 S U
e W
e
28 I8
iW
S
%CIL
% OIL
%
OIL
Flgure.5. Phase diagrams of S-30 as a function of temperature and composition of the third component added as indicated in Figure 4. Labeling follows the scheme of Figure 1. H/SA = 11/5 corresponds to the line beginning at A at Figure 4, W/SA = 1119 to D, WISA = 9/11 to E, WISA = 4 to C, and WISA 9 to B.
Figure 2. Phasc3 diagrams of 575 at various temperatures. The labeling scheme is identical with that of Figure 1.
s-75
SURFACTANT u
H/SA=11/5
Lo W W m W c?
W/SA=I1/9
W/SA=S/Il
W/SA=4
W/SA=9
a
n u CL W I P
2 %
