Table 1.
Thermodynamic and rheological analysis of Langmuir films.
| System composition | MMA (Å2/molec) |
Ka| (mN/m) |
MMA (Å2/molec) |
Ka| (mN/m) |
Phase state | ΔGcompb (cal/mol) |
|---|---|---|---|---|---|---|
| 20 mN/m | 30 mN/m | |||||
| EPCA/W | 87 ± 1 | 61 ± 3 | 74 ± 1 | 75 ± 4 | LE | 410 ± 10 |
| EPC/VAS0.02 A/W | 91 ± 1 | 45 ± 3 | 75 ± 2 | 58 ± 3 | LE | 527 ± 5 |
| EPCO/W (AM) | 104 ± 1 | 62 ± 1 | 90 ± 1 | 71 ± 3 | LE | 465 ± 5 |
| EPCO/W (SM) | 104 ± 1 | 68 ± 5 | 91 ± 1 | 73 ± 1 | LE | 451 ± 9 |
Data were taken from compression isotherms of monolayers of EPC or a pseudo binary mixture of EPC and VAS at 0.02 molar fraction, prepared at the air/water (A/W) or at the VAS/water (O/W) interface. Values are the mean ± S.E.M. of at least two independent experiments. T = 25 ± 1 °C. aCalculated from Eq. 4. bCalculated from Eq. 5 by integrating compression isotherms between 2 and 20 mN/m. The molar fraction of VAS in the EPC:VAS mixture, is indicated as subindex. Phases VAS, W and A, correspond to Vaseline, water and air, respectively.