Small angle neutron scattering study of steroidal gels

Abstract

2014 Des gels formés à partir de solutions diluées dans le cyclohexane de stéroïdes modifiés, sont étudiés par diffusion de neutrons aux petits angles. La présence d'objets très longs associés avec le réseau du gel est mise clairement en évidence. Des experiences de variation de contraste montrent que ces objets sont essentiellement composés par des molécules stéroïdes. Des mesures d'intensités absolues et l'ajustement des courbes de diffusion à des modèles simples suggèrent que ces objets sont chiraux, probablement des doubles hélices symétriques de diamètre d'environ 100 Å. On suggère que les « points de contacts » entre objets sont formés en torsadant deux ou plusieurs de ces longs objets sur des distances relativement grandes par rapport au diamètre. L'influence de ce recouvrement des objets sur la forme des courbes de diffusion est discutée.

Small-Angle Scattering and Electron Microscopy Investigation of Nanotubules Made from a Perfluoroalkylated Glucophospholipid

“…Improving this model is the subject of future investigations to obtain detailed information on these tubules. The discrepancy seen at high Q values is probably due to the polydispersity of the external radius (13). The discrepancy seen at low Q values originates from the interactions between tubules (see Fig.…”

“…These gels were constituted by micron-long rigid fibers (diameter ϳ100 Å) connected by microcrystalline domains. Results were analyzed on the basis of models of symmetrical double helices (13) and simpler cylindrical rods (14), which both gave satisfactory agreement. Similar analyses were carried out for infinitely long fibers with square or rectangular cross-sections present in organogels of 12-hydroxystearic acid or lithium salt (16,17) and cholesteryl 4-(2-anthryloxy)butanoate (18).…”

“…Among the few systems rigorously studied by small-angle X-ray scattering (SAXS) and small-angle neutron scattering (SANS) are some gels formed by a steroid derivative in various organic solvents (13)(14)(15). These gels were constituted by micron-long rigid fibers (diameter ϳ100 Å) connected by microcrystalline domains.…”

Gelation mechanism and microstructure of organogels formed with various types of gelators

“…Organogelators have been gathering much attention during the past decades. [1][2][3][4][5] This is because solidification of oil is very important in industry and daily life, for example, collection of spilled oil from an oil tanker, disposal of waste oil by solidification, viscosity enhancer in foods and cosmetics, and so forth. In addition to the aforementioned practical applications, oil gelators have various interesting aspects from the academic point of view.…”

Low Molecular Weight Gelators for Organic Solvents

“…A well-studied group of organogelators are derived from anthracene and anthraquinone (4,5) [13], or steroids (6) [14], and include also compounds which contain both groups linked via a spacer (7,8) [15,16], Other organogelators of this type are an azobenzenesteroid derivatives (9) [17] and a chiral tetraline derivative (10) [18]. Aggregation of these compounds is based upon π-π stacking and solvophobic effects.…”