Colloidal Particle Growth in Silica Xerogels

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Abstract 9510607 Simeen A new strategy is devised for making colloidal particles dispersed within an inorganic or organic matrix. The sol-gel process is combined with methods for making colloidal particles by homogeneous precipitation from electrolyte solutions. The feasibility of this approach has been demonstrated by successful preparation of a material consisting of large numbers of 0.1-1 micrometer chromium hydroxide spheres embedded within a silica xerogel. Homogeneous precipitation offers the possibility of making a wide variety of particles and the means for exercising systematic control over particle morphology. The goals of the proposed research are to determine whether this technique can be extended to generate particles with different compositions within gels; whether it is possible to create crystalline particles; and whether the metal salt particles can be reduced to metal. Other experiments will investigate the role of the gel matrix in controlling particle size. %%% Synthesis of composite materials consisting of colloidal particles dispersed within an inorganic or organic matrix is of considerable interest because of applications in catalysis and optics, among other areas. A new strategy for making such composites has been devised that combines the sol-gel process with methods for making colloidal particles by homogeneous precipitation from electrolyte solutions. The feasibility of this approach has been demonstrated by successful preparation of a material consisting of large numbers of 0.1-1 micrometer chromium hydroxide spheres embedded within a silica xerogel. Homogeneous precipitation offers the possibility of making a wide variety of particles and the means for exercising systematic control over particle morphology. The goals of the research described in this proposal are to determine whether this technique can be extended to generate particles with different compositions within gels; whether it is possible to create crystalline particles; and whether the metal salt particles can be reduced to metal.