The phase behavior of commercial lipophilic poly(oxyethylene)-poly(dimethylsiloxane) copolymer (PEOS), Me
3SiO(Si(Me)
2O)
x-(SiMe(C
3H
6(OCH
2CH
2)
nOH)O)
ySiMe
3 (x= 50-100, y= 1-5, n= 7-15, HLB value= 5), in water and water + oil systems was investigated by phase study and small angle X-ray scattering (SAXS). The lipophilic PEOS forms a reverse hexagonal liquid crystal (H
2) phase in water, and the H
2 + excess water phase exists at a low concentration. The H
2 phase changes to a reverse micellar cubic (I
2) phase with addition of oil. The I
2 structure is identified to the
Fd3m space group by SAXS. An excess water phase is also coexisted with I
2 phase beyond the solubilization limit of water in the I
2 phase and a large amount of water can be dispersed in I
2 phase as emulsion droplets. As a result, highly viscous or stable gel-emulsion over 96% water as the internal phase could be formulated.
View full abstract