Emulsifying potency of new amino acid-type surfactant (II): stable water-in-oil (W/O) emulsions containing 85 wt% inner water phase.
The ternary phase diagram for N-[3-lauryloxy-2-hydroxypropyl]-L-arginine L-glutamate (C12HEA-Glu), a new amino acid-type surfactant, /oleic acid (OA)/water system was established. The liquid crystal and gel complex formations between C12HEA-Glu and OA were applied to a preparation of water-in-oil (W/O) emulsions. Stable W/O emulsions containing liquid paraffin (LP) as the oil and a mixture of C12HEA-Glu and OA as the emulsifier were formed. The preparation of stable W/O emulsions containing 85 wt% water phase was also possible, in which water droplets would be polygonally transformed and closely packed, since the maximum percentage of inner phase is 74% assuming uniformly spherical droplets. Water droplets would be taken into the liquid crystalline phase (or the gel complex) and the immovable water droplets would stabilize the W/O emulsion system. The viscosity of emulsions abruptly increased above the 75 wt% water phase (dispersed phase). The stability of W/O emulsions with a lower weight ratio of OA to C12HEA-Glu and a higher ratio of water phase was greater. This unusual phenomenon may be related to the formation of a liquid crystalline phase between C12HEA-Glu and OA, and the stability of the liquid crystal at a lower ratio of oil (continuous phase). W/O and oil-in-water (O/W) emulsions containing LP were selectively prepared using a mixture of C12HEA-Glu and OA since the desirable hydrophile-lipophile balance (HLB) number for the emulsification was obtainable by mixing the two emulsifiers.
Yokoyama
S
S
Kyoritsu College of Pharmacy, Tokyo, Japan. yokoyama-sk@kyoritsu-ph.ac.jp
Kouchi
J
J
Tabohashi
T
T
Harusawa
F
F
Yamaguchi
A
A
Sakai
H
H
Abe
M
M
D000465:Algorithms; D000596:Amino Acids / Q000737:chemistry*; D004655:Emulsions; D006863:Hydrogen-Ion Concentration; D007202:Indicators and Reagents; D010232:Paraffin; D013055:Spectrophotometry, Infrared; D013501:Surface-Active Agents / Q000737:chemistry*; D014783:Viscosity; D014867:Water
D000596:Amino Acids; D004655:Emulsions; D007202:Indicators and Reagents; D013501:Surface-Active Agents; D014867:Water; D010232:Paraffin