Pronounced hydrogel formation by the self-assembled aggregates of N-alkyl disaccharide amphiphiles

Bhattacharya, Santanu and Acharya, Ghanashyam SN (1999) Pronounced hydrogel formation by the self-assembled aggregates of N-alkyl disaccharide amphiphiles. In: Chemistry of Materials, 11 (12). 3504-3511 .

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Abstract

Six disaccharide amphiphiles were synthesized and their hydrogel-forming behavior was extensively studied. These amphiphiles were based on maltose and lactose. Since the gels formed from some of these systems showed the ability to "trap" water molecules upon gelation, these gels were described as "hydrogels". When these gels were heated to similar to 70 degrees C, the samples turned into clear, isotropic fluids, and upon gradual cooling, the hydrogels could be reproduced. Thus these systems were also "thermoreversible". The low molecular mass (MW 565) of the gelators compared to that of a typical polymeric gelator forming substance implies pronounced aggregation of the disaccharide amphiphiles into larger microstructures during gelation. To discern the aggregate textures and morphologies, the specimen hydrogel samples were examined by high-resolution scanning electron microscopy (SEM). A possible reason for the exceptionally high water gelating capacities (>6000 molecules of water per gelator molecule) exhibited by these N-alkyl disaccharide amphiphiles is the presence of large interlamellar spaces into which the water molecules get entrapped due to surface tension. In contrast to their single-chain counterparts, the double-chain lactosyl and maltosylamine amphiphiles upon solubilization in EtOH-H2O afforded hydrogels with reduced mechanical strengths. Interestingly, the corresponding microstructures were found to be quite different from the corresponding hydrogels of their single-chain counterparts. Rheological studies provided further insights into the behavior of these hydrogels. Varying the chain length of the alcohol cosolvent could modulate the gelation capacities, melting temperatures, and the mechanical properties of these hydrogels. To explain the possible reasons of gelation, the results of molecular modeling and energy minimization studies were also included.

Item Type:	Journal Article
Publication:	Chemistry of Materials
Publisher:	American Chemical Society
Additional Information:	Copyright of this article belongs to American Chemical Society.
Department/Centre:	Division of Chemical Sciences > Organic Chemistry
Date Deposited:	28 Jun 2011 10:11
Last Modified:	28 Jun 2011 10:11
URI:	http://eprints.iisc.ac.in/id/eprint/38738

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