34 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 60- 40- 30. 20 ' [ ' I ' I ' I ' [ ' I ' I ' I ' [ ' I ' I ' I 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 0.55 0.60 Volume ratio of water/[ TEA+OLA] Figure 7. Interlayer spacings versus water volume ratio for different triethanolamine (TEA)/oleic acid (OLA) weight ratios. TEA/OLA: ß 38/62, ß 35/65, ß 30/70. 701 50- 45 40 35 i i i i i 0 1 2 3 4 Weight ratio of TEA/Water Figure 8. Interlayer spacing for constant oleic acid content (60% by weight) and varied triethanolamine (TEA)/water weight ratio. (TEA + water): OLA = 40:60. such as is the case in the present contribution, and the thickness of the amphiphilic layer, d o (Figure 5), is obtained by extrapolation to a solvent ratio equal to zero. In addition, the slope of the interlayer spacings offers information about the ratio of polar solvent localized in layer A (Figure 5) or of nonpolar solvent localized in layer C. If an assumption is made that the change in solvent content does not cause a modifi- cation of the chain order, B (Figure 5), or alter their tilt, the variation of d with composition becomes d = do(1 + R)/(1 + otR) (1)

LAMELLAR LIQUID CRYSTAL 35 50- 45 • 40 •. 35 ß • 30 25 20 I I I I I 0.00 0.02 0.04 0.06 0.08 0.10 Volume ratio of VE/[TEA+OLA] Figure 9. Small amounts of vitamin E acetate gave no change of interlayer spacing in the water-free systems. TEA/OLA: ß 40/60, ß 35/65, ß 30/70. 50 • 45 •. 40 a3 35 30 25 0.0 011 012 0'.3 014 015 016 Volum ratio of water/[TEA+OLA+VE] Figure 10. Interlayer spacings versus water volume ratio for small amounts of vitamin E acetate (VE). TEA/OLA = 35/65 VE% ß 0, ß3, ß 6. in which R is the solvent to non-solvent volume ratio and o• is the volume fraction of solvent entering layer B (Figure 5) o• is not independent of R but is reduced for higher values of it. Hence, the limit of o• for R--) 0 is used to characterize the solvent penetration o• = ! - (Od/OR)/d o (2) R--)0 Applying these equations to the present results provides the following information. Formally, triethanolamine in the oleic acid/triethanolamine liquid crystal is evenly