Sains Malaysiana 43(4)(2014): 623–628

Microscopic Study of AOT and CTAB Anionic-rich Catanionic Phase

(Kajian Mikroskopik Anionik-kaya dalam Fasa Katanionik AOT dan CTAB)

CHUN YUAN TAN¹, KOK SIONG KHOO²*, SHAHIDAN RADIMAN², IRMAN ABDUL RAHMAN²& NUR FARHANA BT AMARI³

¹Centre of Foundation Studies, Universiti Tunku Abdul RahmanBuilding PE, No. 1, Jalan 13/4, 46200 Petaling Jaya, Selangor Darul Ehsan, Malaysia

²School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia

43600 UKM Bangi, Selangor, Malaysia

³Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor, Malaysia

Diserahkan: 10 Ogos 2012/Diterima: 22 Julai 2013

ABSTRACT

Catanionic system using anionic sodium bis-(2ethylhexyl)sulfosuccinate (AOT) and cationic cetyltrimethylammonium bromide (CTAB) is studied. The system is prepared by addition of CTAB solution to a prepared AOT solution until slight anionic-rich catanionic phase is produced. Catanionic system consists of the mixture of different types of surfactants and counterion due to electrostatic interaction between the oppositely charged surfactant. Both of these products affect the in surface activity of the surfactant. Hydrodynamic diameters decrease and clearer solution were seen with the increase of CTAB concentration in solution mixture. As a result, mixed surfactant with larger hydrophobic region and the presence of counterion will induce smaller vesicle to form in catanionic system.

Keywords: Alkyl chain number; anionic-rich phase; catanionic system; electrostatic interaction; surfactant number

ABSTRAK

Sistem katanionik dengan menggunakan anionik natrium bis-(2etilheksil)sulfosuccinat (AOT) dan kationik cetiltrimetilammonium bromida (CTAB) telah dikaji. Sistem ini disediakan melalui penambahan larutan CTAB kepada larutan AOT yang disediakan sehingga fasa kationik yang beranionik terhasil. Sistem kationik ini mengandungi dua jenis surfaktan yang berbeza dan garam disebabkan kewujudan interaksi elektrostatik pada perbezaan cas dalam surfaktan. Bahan hasilan ini memberi kesan kepada aktiviti permukaan surfaktan. Garispusat hidrodinamik menurun dan larutan menjadi jernih dengan penambahan kepekatan CTAB kepada larutan AOT. Kesimpulannya, hasil surfaktan baru dengan bahagian hidrofobik yang lebih besar dan garam akan mengaruhkan vesikel yang kecil terbentuk dalam sistem katanionik.

Kata kunci: Fasa anionik-kaya; interaksi elektrostatik; nombor rantai alkil; nombor surfaktan; sistem katanionik

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*Pengarang untuk surat-menyurat; email: khoo@ukm.my