Hydrotrope and Hydrotrope-Solubilization Action of Urea in CTAB/n-C5H11OH/H2O System

Polyvinylacetate-SiO2 gels have been obtained by radical polymerization of vinyl acetate (VAc) in the presence of tetraethoxysilane (TEOS). The reaction system was: VAc:TEOS:EtOH:H2O:S (nonylphenol ethoxylated with 25 moles ethylene oxide) in different ratios. The reaction was performed at 65°C. The initiator of radical polymerization was benzoyl peroxide and a crosslinking agent of sol-gel process bis maleate of diethylene glycol. Traces of acetic acid, maleic acid or acrylic acid catalyze the polymerization of TEOS. The presence of the surfactant (S) ensures the homogeneity of the initial system. The conditions of obtaining homogeneous gels have been selected. Ternary diagrams containing TEOS:EtOH2O or (VAc+TEOS):EtOH2O:S were used in order to establish the domains of homogeneous compositions in the systems. Refractometric and conductometric measurements have shown that the mentioned systems are microemulsions. X-ray diffraction, surface area measurements, DTA/TGA method, as well as IR spectrometry have been used in the characterization of the gels obtained.