Short Chain Sugar Amphiphiles: Alternative Oil Structuring Agents

Owing to the need of developing environmentally benign functional materials by adopting green chemistry methods, usage of biorefinery concept for the development of biobased molecular building blocks of such materials has emerged as a prime focus of the current research. The present study focus of developing sugar based low molecular weight gels (a type of functional soft materials) by enzyme catalysis exemplifies the above approach. The underexplored open chain sugars (sugar alcohols) were chosen as hydrophilic moieties to develop low molecular weight gelators (LMWGs). Mannitol, sorbitol and xylitol were selected as representative sugar alcohols (headgroups) and series of amphiphiles were synthesized by attaching hydrophobic carboxylic acids at one-end of the sugar using an enzyme-mediated regioselective transesterification reaction. For control tuning of hydrophobicity various carboxylic acids different chain length were attached (typically (CH2)4-14). The resulting amphiphiles were studied for their self-assembling behavior in organic liquids. Only the amphiphiles with short chains {(CH2)4-8} were found to be efficient organogelators; immobilizing various solvents ranging from crude oil fractions to vegetable oils. In addition, Effect of chiral and structural variations in sugar amphiphiles on microstructure formation (responsible for immobilization of organic liquid) was also investigated in detail. Furthermore, the efficiency of the short chain sugar amphiphiles as a healthy alternative structuring agents for vegetable oils compared to existing oil structuring agents was studied and has been demonstrated in this report.