Abstract
The binary phase diagrams of certain diglycerol alkyl ethers (DGE) and water systems were determined and the solution behavior of these surfactants was studied.
These surfactants form liquid crystalline phases with lamellar structures even at low concentrations at which ordinary nonionic surfactants with ethylene oxide chain give micellar solution.
Aqueous solutions of 1% to 2% of DGE showed coloration which changed according to surfactant concentration.
Furthermore, the color of these solutions observed by reflected light differed from that observed by transmitted light. On the basis of the phase diagram study and scanning electron micrographic determination, the structure of these colored solutions was concluded to be a dispersion of multi-lamellar liquid crystals containing large amounts of water within the interlayers.
The coloration was thus considered to arise from the interference of light reflected at the interface of lamellar layers whose thickness was comparable to that of the wave length of visible light.
