Abstract
The five-component system is quite unique since it allows formation of reverse micelles with hydrophilic ethoxylated alcohol in the presence of ethanol and it facilitates dilution by water/propylene glycol (1,2-propanediol, PG) aqueous phase, all the way from a water-in-oil (W/O) microemulsion via a bicontinuous phase to an oil-in-water (O/W) microemulsion. The surfactant/alcohol/PG can strongly bound water in the inner phase so that it freezes below -10°C and acts in part as 'bound' water and in part as 'non-freezable' water. Upon dilution to >30 mass% aqueous phase (water/PG at constant mass ratio of 1/1) the system becomes bicontinuous and the aqueous layers are composed again from bound water. Even after complete inversion to O/W microemulsions the water in the continuous phase is strongly interacting with the PG/surfactant and remains bound or non-freezable. Water/PG/ethanol have a strong effect on the head groups (freezing below -10°C) and also on the hydrophobic tails (recrystallizing and melting) at lower temperature when dilution exceeds 45 mass% water/PG (1/1). No free water was detected neither in the W/O microemulsion's inner droplet domains nor when the microemulsion was either bicontinuous or when it was inversed to O/W. Continuous phase of resulting O/W microemulsion apparently is based on water/PG at a mass ratio of 1/1.
| Original language | English |
|---|---|
| Journal | Journal of thermal analysis and calorimetry |
| Volume | 69 |
| Issue number | 1 |
| Pages (from-to) | 163-177 |
| Number of pages | 15 |
| ISSN | 1418-2874 |
| DOIs | |
| Publication status | Published - 26 Aug 2002 |
Keywords
- Differential scanning calorimetry
- Interphasal water
- Non-freezable water
- Non-ionic microemulsions
- Propylene glycol