Qualitative analysis of mixed surfactants systems: Synergism and antagonism

Historically, the use of anionic and cationic surfactants in a formulation was a practice that was shunned. Mixed anionic/cationic surfactant systems were evaluated were evaluated back in 1981(1, 2).The notion that stable, clear and foaming aqueous combinations of anionic / cationic surfactants could be made using specific surfactants and specified combinations 2005(3, 4, 5, 6).

Systems having two types of surfactant (binary systems) have been studied (1). This article expands to systems having three types of surfactants so-called ternary systems.

1. Brassicamidopropyl Dimethylamine (Procondition 22, 100% a.m.),

2. Behentrimonium Chloride (Quartamin AB, 80% a.m.),

3. Cocamidopropyl Betaine (Probetaina CAPB, 30% a.m.),

4. Cetrimonium Chloride (Sunquart CT29, 29% a.m.),

5. Decyl Glucoside (DG Surfactant, 50% a.m.),

6. Disodium Lauryl Sulfosuccinate (Cosphactant MES 30, 30% a.m.),

7. Dihydrogenated Tallowoylethyl Hydroxyethylmonium Methosulfate (and) Ditallowoylethyl Hydroxyethylmonium Methosulfate (Tetranyl AT-7590, 90% a.m.),

8. Sodium Hydroxypropylsulfonate

9. Laurylglucoside Crosspolymer (Poly SugaNate 160P NC, 40% a.m.),

10. Sodium Cocoyl Glycinate (Miami SCG, 25%),

11. Sodium Laureth-2 Sulfate (Mathless, 70% a.m.),

12. Sodium Laurylglucosides Hydroxypropylsulfonate (SugaNate 160NC, 40% a.m.).

CTC – Cetrimonium Chloride

DLSS – Disodium Lauryl Sulfosuccinate

PSN – Sodium Hydroxypropylsulfonate Laurylglucoside Crosspolymer

SCG – Sodium Cocoyl Glycinate

SLES – Sodium Laureth-2 Sulfate

SN – Sodium Laurylglucosides Hydroxypropylsulfonate

Solutions were prepared at different concentrations of surfactants. Mixing ratios are expressed as weight percentages. The room where all tests were carried out was set at 65% RH and 20±0.1°C.

Appearance

Visual inspection was performed placing surfactant aqueous mixtures in transparent 100mL borosilicate glass beakers, which were then placed in a well illuminated room to check for possible formation of precipitates. Samples were rechecked after 24 hours, in case new precipitates would have appeared.

Viscosity

Viscosity measurements were carried out on a digital Brookfield LVT viscometer with appropriate thermostating (±0.1°C), and using the spindle #64. Three different speeds were used for each sample: 6, 30 and 60 rpm.

Ternary systems of anionic-cationic-amphoteric surfactants were also studied. In the first part SLES was chosen as the anionic surfactant, while CTC and CAPB were the cationic and amphoteric surfactants, respectively. Table 1 shows viscosity and appearance results when mixing all the surfactants at different ratios.

The same evaluation was done, replacing SLES by DLSS. The results are shown in Table 2.

Another anionic surfactant tested was SCG. The results of that test are shown in Table 3.

As in our previous tests, both glucoside anionic surfactants show almost no viscosity response both when mixing them only with CTC, and when CAPB was added after (Tables 4 and 5). This can also be explained by the bulky polar head group present in both surfactants.