Effect of surfactant and surfactant blends on pseudoternary phase diagram behavior of newly synthesized palm kernel oil esters

BACKGROUND The purpose of this study was to select appropriate surfactants or blends of surfactants to study the ternary phase diagram behavior of newly introduced palm kernel oil esters. METHODS Nonionic surfactant blends of Tween(®) and Tween(®)/Span(®) series were screened based on their solubilization capacity with water for palm kernel oil esters. Tween(®) 80 and five blends of Tween(®) 80/Span(®) 80 and Tween(®) 80/Span(®) 85 in the hydrophilic-lipophilic balance (HLB) value range of 10.7-14.0 were selected to study the phase diagram behavior of palm kernel oil esters using the water titration method at room temperature. RESULTS High solubilization capacity was obtained by Tween(®) 80 compared with other surfactants of Tween(®) series. High HLB blends of Tween(®) 80/Span(®) 85 and Tween(®) 80/Span(®) 80 at HLB 13.7 and 13.9, respectively, have better solubilization capacity compared with the lower HLB values of Tween(®) 80/Span(®) 80. All the selected blends of surfactants were formed as water-in-oil microemulsions, and other dispersion systems varied in size and geometrical layout in the triangles. The high solubilization capacity and larger areas of the water-in-oil microemulsion systems were due to the structural similarity between the lipophilic tail of Tween(®) 80 and the oleyl group of the palm kernel oil esters. CONCLUSION This study suggests that the phase diagram behavior of palm kernel oil esters, water, and nonionic surfactants is not only affected by the HLB value, but also by the structural similarity between palm kernel oil esters and the surfactant used. The information gathered in this study is useful for researchers and manufacturers interested in using palm kernel oil esters in pharmaceutical and cosmetic preparation. The use of palm kernel oil esters can improve drug delivery and reduce the cost of cosmetics.