Liquid crystal and emulsifying properties of carboxymethyl glucoside as water-soluble surfactant

Abstract

ABSTRACT Three derivatives of glucosides derived from n-dodecyl alcohol in a highly pure β-anomer were synthesised with the aim to yield the liquid crystalline phase at ambient temperature with improved water solubility. Effect of variation in headgroup polarity on thermal properties, liquid crystalline phases, and structures of these derivatives of n-dodecyl β-D-glucoside (β-GlcC12) has been examined through differential scanning calorimetry, optical polarising microscopy, and small- and wide-angle X-ray scattering, respectively. Derivative bearing two carboxymethyl and two hydroxyl groups at the sugar ring i.e. n-dodecyl 2,3-bis-O-[carboxymethyl]-β-D-glucopyranoside (2,3-diCOOH-β-GlcC12) exhibited lamellar phase at the room temperature in anhydrous condition by significantly reduced the melting and clearing temperatures compared to parent compound β-GlcC12. Under excess water condition, 2,3-diCOOH-β-GlcC12 was completely soluble to form a normal micellar solution. We further investigated its foaming performance and emulsifying ability in n-octane, n-dodecane, and n-hexadecane as the oil phase. Both aqueous solution of 2,3-diCOOH-β-GlcC12 emulsified with n-dodecane and n-hexadecane formed oil-in-water emulsion layer of more than 95% of the total system volume with n-dodecane/water system consistently maintains smaller particle sizes and a narrower polydispersity index. This supports the stronger emulsifying ability and better colloidal stability of the 2,3-diCOOH-β-GlcC12 in the n-dodecane/water system than in the n-hexadecane/water system.