Hydrocarbon gels from water-in-oil microemulsions

Abstract

A procedure is described that permits the transformation of hydrocarbon microemulsions into gels. This is obtained by cooling a previously heated isooctane solution of bis(2-ethylhexyl) sodium sulfosuccinate containing 10-20% of an aqueous gelatin solution. The final system is a homogeneous gel, whose consistency and physical properties vary depending upon the relative concentration of water and gelatin. These new hydrocarbon gels have been investigated with 'H NMR, circular dichroism, differential scanning calorimetry, and electron microscopy. Enzymes and bacteria can be entrapped in apolar gels without loss of activity. IntroductionSeveral papers have appeared describing the properties of proteins hosted in reverse micelles.'-5 The system of choice is bis(Zethylhexy1) sodium sulfosuccinate (AOT)/isooctane/water, due mostly to the fact that this system permits water solubilization over a wide range of w, (w, = [HzO]/[AOT]) values6g7 (at high w, values the term water-in-oil microemulsions is more accurate than reverse micelles).As a result of the micellar environment, proteins acquire novel physical and conformational properties, which has lead to an interesting research perspective from both the biophysical and the biotechnological points of In this paper, we will describe a particular effect caused by the solubilization of gelatin in water-in-oil microemulsions. As is well-known, gelatin is able to form gels in water.15 This is generally obtained by cooling concentrated solutions from above 40 "C to approximately 35 "C or below, a phenomenon that is the basis of an industrially important process and one that is very interesting from the point of view of structural protein chemistry. Since gelatin can be solubilized in reverse micelles,I0 it appeared interesting to investigate how the micellar environment affects this protein gelling behavior. Our expectation was that gel formation would take place within the water pools of the reverse micelles, eventually bringing about a clouding of the hydrocarbon micellar solution and possibly phase separation of the aqueous gel. Something completely different takes place: the whole micellar solution becomes a gel. This paper describes the preparation of these novel materials and their basic physical properties and gives indications of some possible application in the area of applied biochemistry.

Synthesis and Structure–Property Relationships of Amphiphilic Organogelators

“…The field of organogelators has attracted interest due to industrial applications in many areas such as cosmetics, polymers, and soft condensed matter with advanced functions. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] The process of these self-assembly-type gelators is driven by specific noncovalent intermolecular interactions. The physical gels formed are therefore thermoreversible.…”

Biocatalysis using lipase encapsulated in microemulsion-based organogels in supercritical carbon dioxide

“…The gel matrix formed by a gelling agent, such as gelatin, fully retains the surfactant, water and enzyme components and can be handled as an immobilized biocatalyst that facilitates the diffusion of non-polar substrates and products. The preparation of MBGs was first reported in 1986 [6][7][8] and subsequent spectroscopic investigations [9,10] have shown that the microemulsion structure is well preserved in the network of the gels, which are believed to contain a more or less bicontinuous phase that may co-exist with conventional w/o microemulsion droplets. MBGs containing immobilized lipase were applied for the preparative scale synthesis of miscellaneous esters and both regio-and stereoselectivity have been observed [11][12][13][14][15][16][17][18][19][20][21].…”

Organo-gel de heptano: diagrama de fases e aplicações sintéticas

“…A formação do organo-gel foi primeiramente descrita em 1986, [15][16] e sua caracterização física/estrutural tem sido alvo de vários estudos [17][18][19][20][21] .…”