Modulating the physical properties of sunflower oil and sorbitan monopalmitate-based organogels

The present study deals with the modulation of the sunflower oil (SO) and sorbitan monopalmitate (SM) organogels using water. The gels were prepared by heating either SOSM mixture or SOSMwater mixture at 60 degrees C and subsequently cooling the mixture to room temperature. The gels were characterized by microscopy (light and electron), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), differential thermal analysis, rheometry, pH, dc impedance, hemocompatibility, and antimicrobial studies. The gels without water (G) were found to be pale yellow in color while gels containing water (GW) were white in color. Both types of gels were thermoreversible in nature. The microscopic analysis revealed that clusters of rod-shaped tubules were responsible in the formation of network. GW also showed the presence of water droplets encapsulated within the networked structure. FTIR studies indicated the presence of intermolecular hydrogen bonding, responsible for gel formation. Gel-to-sol transition temperatures (Tgs) of the GW gels were higher than G gels, which might be accounted to the higher crystallinity of the GW gels. XRD studies confirmed the higher crystallinity of the GW gels. The gels showed pseudoplastic flow behavior and were hemocompatible in nature. Ciprofloxacin-loaded gels showed good anti-microbial properties against Bacillus subtilis. Based on the preliminary results, the developed gels may be used as delivery vehicles for various bioactive agents. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013