LAMELLAR LIQUID CRYSTAL 33 A B C B A Figure 5. the lamellar liquid crystal may be viewed as consisting of three zones: A, water B, methylene groups and C, terminal methyl group layers. 5O 45 • 40 • 35 • 30 25 20 i i o.o o.'• o.'• o.'• 0.4 o.'• o•6 o17 0.8 Volume ratio of TEA/OLA Figure 6. Interlayer spacing in the water-free system (Figure 1) versus the triethanolamine (TEA)/oleic acid (OLA) volume ratio. DISCUSSION The results provide information about the behavior of vitamin E acetate in the lameliar liquid crystal from the interlayer spacings calculated from the low-angle x-ray results. These provide direct information about the variation of the interlayer spacing, d (Figure 5) as a function of composition. The variation with solvent is commonly a straight line,

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)