Effects of apolar organic additives on phase behaviors of cationic-anionic surfactant mixtures

Abstract

This study explores the effects of apolar organic additives (AOAs) of n-hexane, cyclohexane, 1,3,5-trimethylbenzene (TMB) and 1,3,5-triisopropylbenzene (TIPB), on the expansion of hydrophobic space of liquid crystals. The results showed that the ordered assemblies of cationic-anionic surfactant mixtures still existed in presence of four different AOAs, indicating that AOAs were successfully embedded into the hydrophobic environments of the ordered assemblies without destroying ordered structures. Although AOAs were solubilized into the systems, the solubilization capacities were obviously different. It was found that the straight-chain alkanes penetrated into the mixed systems more easily than the cyclic AOAs with large steric hindrance. Besides, for cyclic AOAs (cyclohexane, TMB and TIPB), more complex structures were more sensitive to temperature. It was observed that the range of cationic liquid crystal (LCc) with CTAB in excess extended larger with the higher temperature in the mixed system containing TMB.

Graphical Abstract

Keywords:

• Cationic-anionic surfactant mixtures
• apolar organic additives
• phase behavior
• solubilization capacity

Additional information

Funding

This work was supported by the Qingdao Science and Technology Project under the contract number 17-3-3-84-nsh.