Table 2.
Stabilization of wetting, foam and O/W emulsion films using various types of nonionic polymeric surfactants.
| Surfactant Type | Research Methodology | Major Findings | References |
|---|---|---|---|
| Inutec®SP1 | Microinterferometric technique of Scheludko–Exerowa was used to measure the stability of foam films at a constant concentration of Inutec®SP1 (2 × 10−5 mol dm-3) and at several NaCl concentrations (1 × 10-4 to 2 mol dm-3). | The film thickness was significantly decreased with increasing NaCl concentration, which indicated the stability of the foam film. At 1 × 10−2 mol dm-3 NaCl, the film thickness remained constant at approximately 16 nm. | Exerowa et al. (2006) |
| Inutec®SP1 | The microinterferometric method for investigation of thin liquid films described in the monograph of Exerowa-Kruglyakov against a constant concentration of Inutec®SP1 (2 × 10−5 mol dm-3) and at quite a few NaCl concentrations. | The O/W emulsion film thickness was approximately 11 nm. The film thickness could be decreased at critical NaCl concentration 5 × 10−2 mol dm-3. | Exerowa et al. (2007) |
| Inutec®SP1, Block and Triblock copolymeric surfactant | The microinterferometric thin liquid pressure balance experimental technique was used to calculate the stability of O/W emulsion films against varying NaCl concentrations | Emulsions using Inutec®SP1 should be more stable than those using Pluronics ABA copolymers, in particular at high electrolyte concentrations. | Exerowa, Gotchev, Gotchev et al. (2009b) |
| HMI-A, HMI-B, HMI-C, Inutec®SP1 | The microinterferometric technique of Scheludko–Exerowa was used to identify the stability of O/W emulsion films at a constant concentration of surfactants (2 × 10−5 mol dm-3) and multiple concentrations of NaCl. HMI-A, HMI-B, and HMI-C were prepared by changing the DS. Thus, one would expect the loop size to decrease as follows: HMI-A > INUTEC®SP1 >HMI-B >HMI-C. | The film thickness was markedly decreased with increasing NaCl concentration at a certain level (5 × 10−2 mol dm−3). In all cases, these NBFs are very stable and have a constant thickness up to the highest possible measured capillary pressure of 45 kPa. With the polymeric surfactant possessing the highest DS, the transition to an NBF of thickness 7 nm occurs even at a low capillary pressure of 36 Pa. With a reduction in DS, the loop size increases, and the transition to an NBF of 7 nm occurs at a higher capillary pressure of 0.5 kPa | Exerowa, Gotchev et al. (2009c) |
| Inutec®SP1 | The microinterferometric technique of Scheludko–Exerowa was designed to find the stability of O/W emulsion films against different types of electrolytes (Na2SO4 NaCl and Mg2SO4). | The film thickness significantly decreased and produced NBFs in all types of electrolyte at a specific capillary pressure, with no observed influence of electrolyte types on the equivalent film thickness, the formation of NBF and disjoining pressure-equivalent film thickness isotherms. | Gotchev et al. (2007) |
| Inutec®SP1 | The microinterferometric technique of Scheludko–Exerowa was used to measure the stability of wetting films produced on a hydrophilic silica surface. The stability was evaluated against different Inutec®SP1 concentrations in the presence or absence of Na2SO4 and NaCl. | The equilibrium film thickness varied with increasing electrolyte and polymeric surfactant concentrations. The reduction pattern in the equilibrium film thickness can be observed at 10−1 mol dm−3 NaCl, 10−6 mol dm−3 Inutec®SP1 and 10−2 or 1 mol dm−3 Na2SO4. | Nedyalkov et al. (2007) |
| Inutec®SP1, HMI-B, EFKA-4550 | The microinterferometric technique of Scheludko–Exerowa was used to measure the stability of wetting films against different types of polymeric surfactants at varying DSs. | The wetting films were stable at (Øw ≤25°) for Inutec®SP1 and (Øw ≤20°) for HMI-B. The general trend of change of h with CEFKA is similar to that obtained for Inutec®SP1 and HMI-B. | Nedyalkov et al. (2010) |
| Inutec®SP1 | The microinterferometric method for investigating the wetting and O/W emulsion films described in the monograph of Exerowa-Kruglyakov both in aqueous solution and in the presence of different electrolytes (NaCl, Na2SO4, and MgSO4) concentrations have been studied. | Emulsion and wetting films could be stabilized using HMI surfactants in the presence of all different types of electrolytes at varying concentrations. | Exerowa, Platikanov et al. (2009d) |
| Inutec®SP1, 0.5HMI, 2HMI 3HMI. | The thin liquid film–pressure balance technique has been used to measure the stability of foam and O/W emulsion films against different types of polymeric surfactants that are synthesized by altering the DS. Thus, one would expect the inulin loop size to decrease as follows: 0.5HMI > Inutec®SP1 > 2HMI > 3HMI. | NBFs have been found in all types of inulin-based surfactants and had the same thickness of approximately 7 nm. Foam films are unstable at 8 kPa for 2HMI and 150 Pa for 3HMI, whereas for 0.5HMI and Inutec®SP1, the foam films are stable at 100 kPa. Due to the formation of NBFs, the O/W emulsion films are more stable, up to 45 kPa in all HMI synthesized derivatives. | Gotchev et al., 2011. |
O/W = oil-in-water, NBF = Newton black film, HMI-A, HMI-B, HMI-C and 1HMI, 2HMI, 3HMI = Different types of inulin derivatives with different DSs. DS = degree of substitution.