The W/O, O/W microemulsion and the lamellar liquid crystal (LC) are formed in the DBS/C~1~0H~2~1OH/Solvent system when formamide, water and glycerol are used as solvent respectively. The distribution coefficient K of C~1~0H~2~1OH in DBS micellar system is very high in any of the three solvents. The LC is formed in the appropriate concentration range of DBS when formamide or water is used as solvent. However LC is not formed when glycerol is used as solvent. The proper amount of addition of C~1~0H~2~1OH is advantageous to the formation of the LC. At the same weight ratio of decanol/DBS, both the solvent penetration α and d~0 in the lamellar liquid crystal decrease in the order of water, formamide and glycerol. The order degree, Δν, of solvent in LC shows higher values in formamide medium, lower values in water medium and median values in glycerol medium. The molecular orientation of the DBS in the amphiphilic bilayer of the lamellar liquid crystal is parallel to the influence of the solvent-property on the stability of the lamellar liquid crystal.

Key words: SURFACTANTS, MICROEMUSION, LAYER STRUCTURE, LIQUID CRYSTAL, DODECYLBENZENESULFONATE, SODIUM SALT, PHASE DIAGRAM, SOLVENTS, FORMAMIDE, WATER