New carbohydrate amphiphiles, 2. Gel formation and gel morphologies

Abstract

The physical gelation of 3,4,5-trialkoxy-N-( 1-deoxysorbitol-1-y1)benzamides and 3,4,5-trialkoxy-N-(2-deoxyglucos-2-yl)benzamides in organic solvents and monomeric methacrylates at ambient temperature is reported. UV polymerization of the methacrylate solvent yielded interpenetrating networks of the crosslinked polymethacrylate and the aggregated solute. The embedded gels exhibit two different morphologies depending on the solvent. Either whitehubid gels containing a percolating network of globular aggregates (@ = 1 -10 pm) or clear, transparent gels consisting of rod-like crystals (0 = 4-100 nm) were found. The sphere morphology consists of small rod-shaped crystallites assembled to spherical objects and is assumed to be caused by a liquid-liquid demixing process prior to gelation.

Gelation with Small Molecules: from Formation Mechanism to NanostructureArchitecture

“…Although the structure of fibrous networks of supramolecular materials is very important with respect to the macroscopic properties [1][2][3][4][5][6][7][8][9] and has the typical characteristic of the Cayley fractal tree, the measurement of the fractal dimension D f remains as a challenging issue owing to the lack of an effective method. Since the average length of the branches is essentially above microns and there is a problem associated with multiple scattering, the fractal structure of this type of fibrous network is difficult to measure by the conventional light scattering method [59,60].…”

“…Other research groups including those of Terech, Hanabusa, Weiss, Shinkai, and Boden all made significant contributions towards the design of novel gelling agents and the understanding of the gelation phenomena [6,7,11]. Important guidelines for the design of novel gelling agents that emerged from these studies are:…”

“…Pioneering work on smart polymer gels which could reversibly swell or shrink upon exposure to some chemical or physical triggering event has been carried out by Tanaka [81]. Recently, the group of Tanaka developed a novel gel system which can bind guest molecules by multiple-point noncovalent interactions [82]. Most interestingly, swelling of the gel induced by a temperature change increases the distance between the individual interaction points.…”

“…In recent years there has been rapidly growing interest in such materials, which is motivated by the many potential applications in photographic, cosmetics, food, and petroleum industries, drug delivery, lithography, catalyst supporters, scaffolds for tissue engineering, the novel separation for macromolecules, etc. [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Supramolecular functional materials with 3D fibrous network structures can be employed as a vehicle for drug delivery and controlled release.…”

“…Consequently, self-supporting supramolecular materials will be obtained [8][9][10][15][16][17][18][19][20][21]. In contrast, systems consisting of nonpermanent/or transient interconnecting (or entangled) fibers or needles can only form weak and viscous paste at low concentrations [6,7].…”