Evidence of Fractal Network Formation in Gelatin-W/O Microemulsions

Abstract

The scattering properties of gelatin containing WiO microemulsions near the sol-gel transition are discussed. The fractal dimension of the aggregates and network is found to be 1.65 k 0.05 for length scales larger than the radius of gyration of the gelatin containing aqueous microemulsion droplets (nanogels, R , = 30 nm from light scattering). At smaller length scales (SAX-scattering) the interface of the droplets appears relatively rough with a surface fractal dimension D, = 3.0. The results agree with the concept of a network being built up by polymers cross-linking the nanogels.

Effect of the Addition of Water-Soluble Polymers on the Structure of Aerosol OT Water-in-Oil Microemulsions: A Fourier Transform Infrared Spectroscopy Study

“…3 However, there is not enough information about the polymer-surfactant interaction or about the effects of the polymer on the droplet structure, size, and shape. Most of the works have studied these microemulsions in the domain of the gel formation using the gelatin agents, [4][5][6] but a better understanding of such systems requires modified conditions of formation for these microemulsions, i.e., varying the kind of polymer, the polymer content, or the water composition.…”

Application of the Temperature-Ramped Holographic Relaxation Spectroscopy in the Investigation of Physically Cross-Linked Gels

“…The gelatin gel is a typical physical gel. It can undergo a thermoreversible gelation if the gelatin concentration is higher than 2−3 wt %. − Most of the past studies were focused on the investigations of its conformation change in solution, the sol−gel transition, and its rheological properties because it is one of the most abundantly found proteins in mammals and also because it has various industrial applications. − It is generally known that the sol−gel transition involves a renaturalization process; namely, the gelatin chains form fibrous triple-stranded helixes, and the aggregation of these helixes leads to small crystal junctions which act as cross-linking points and build up a three-dimensional gel network. However, the exact conformational path has not been conclusively established yet.…”

Dynamic Light Scattering and Infrared Spectroscopic Studies of the Interaction of Poly(vinylpyrrolidone) Polymers with Aerosol OT/Isooctane Water-in-Oil Microemulsions

“…Recent work in this field has centered upon the effect of additives on the size, [4][5][6] on the electrical percolation processes, [7][8][9] or on the formation of microemulsion gels. [10][11][12] In a previous paper, 13 we have reported results concerning the effect of the addition of poly(vinylpyrrolidone), PVP K15 (MW ) 10 000 g/mol), and poly(sodium 4-styrene sulfonate) polymers on the structure of w/o microemulsions of sodium bis(2-ethylhexyl)sulfosuccinate, AOT, dissolved in toluene. Infrared spectra of these microemulsions show that the addition of polymers changes the water pool structure as regards the corresponding one for empty microemulsions, whereas no significant changes in the interfacial properties were detected.…”

“…Correct use of these microemulsions requires knowledge of their size, of their size distribution, and of their structural properties. Recent work in this field has centered upon the effect of additives on the size, − on the electrical percolation processes, − or on the formation of microemulsion gels. − …”