Surface Properties and Liquid Crystal Properties of Alkyltetra(oxyethyl) β-d-Glucopyranoside

Abstract

Hydrophilic alkyl polyglycosides (APGs) and alkyl glycosides (AGs) with anomeric pure are a class of important substitutes for petroleum-based surfactants. Improving their water solubility should make such hydrophilic glycosurfactants have more excellent potential application value. To solve the inherent problem of poor water solubility of traditional alkyl β-Dglucopyranoside (5), a series of alkyltetra(oxyethyl) β-D-glucopyranosides (4a−4g, n = 7−18) were successfully synthesized by introducing tetra(oxyethylene) fragments to carry out the structural modification. The relationship between the related structure and the physicochemical properties was further investigated, including their hydrophilic−lipophilic balance (HLB), water-solubility, foaming performance, emulsification, hygroscopicity, surface activity, and thermotropic/lyotropic liquid crystal phase behavior. The results showed that the water solubility gradually decreased as the alkyl chain length increased due to the gradual decrease of their HLB number. Octadecyltetra(oxyethyl) β-D-glucopyranoside (4g, n = 18) was found to be insoluble in water at 25 °C. Taken together, long-chain alkyl glycosides had good foaming properties and excellent emulsifying properties. Among them, dodecyltetra(oxyethyl) β-D-glucopyranoside (4d, n = 12) had the best foaming performance. In the rapeseed oil/water system, cetyltetra(oxyethyl) β-D-glucopyranoside (4f, n = 16) had the best emulsifying ability. With the increase of the alkyl chain length, the critical micelle concentration (C cmc ), γ cmc , Γ max , and hygroscopicity of this series of glycosides showed a downward trend. Differential scanning calorimetry (DSC) and polarizing optical microscopy (POM) showed that the thermal stability increased with the increase of the alkyl chain length, and alkyltetra(oxyethyl) β-D-glucopyranosides (4d−4g, n = 12−18) had the corresponding melting points and clearing points. Alkyltetra(oxyethyl) β-D-glucopyranosides (4b−4g, n = 8−18) formed a smectic phase with a typical fan-shaped and focal conic texture during the cooling process. In the water contact experiments, it was found that glycosides (4b−4g, n = 8−18) at high concentrations transformed into various lyotropic liquid crystal including hexagonal phase, bicontinuous cubic phase, and lamellar phase phases. Therefore, such green nonionic glycosurfactants alkyltetra(oxyethyl) β-D-glucopyranosides should have potential practical application prospects.

Surface Properties of Alkyldi(oxyethylene) β-D-Maltoside

“…Thermotropic liquid crystals of alkyl glycosides have received extensive research in recent years. , From the view of the related configurations, maltose and glucose should be considered to have some differences so that their thermotropic liquid crystal behaviors should probably be different from each other to some extent.…”

Cubosomes and Hexosomes as Novel Nanocarriers for Bioactive Compounds

“…15−18 The bioactives that have been successfully encapsulated using cubosomes and hexosomes include flavor compounds, vitamins, carotenoids, phenolics, peptides, and other nutraceuticals. 19,20 In this context, this review article focuses on the promising cubosomes and hexosomes for encapsulation, protection, and controlled delivery of bioactive compounds. The structure, composition, preparation methods, and advantages are discussed on the basis of the recent literature (Table 1).…”

“…The food-related bioactive compounds have been emerged as a health-beneficial therapeutic agent, which potentiate the design of functional food products and novel supplements. However, most of them are susceptible to chemical or biochemical degradation, limiting their shelf life, oral absorption, and bioavailability. − The bioactives that have been successfully encapsulated using cubosomes and hexosomes include flavor compounds, vitamins, carotenoids, phenolics, peptides, and other nutraceuticals. , In this context, this review article focuses on the promising cubosomes and hexosomes for encapsulation, protection, and controlled delivery of bioactive compounds. The structure, composition, preparation methods, and advantages are discussed on the basis of the recent literature (Table ).…”