Surface Modification of Layered Zirconium Phosphates: A Novel Pathway to Multifunctional Nanomaterials

Abstract

The surface functionalization of inorganic nano particles for improved and novel applications is the topic of this dissertation; specifically the surface modification of inorganic layered materials. In this case the goal is to exclusively modify the surface or exterior layers of the material, while leaving the internal layers and structure unchanged. This allows for organic derivatives of layered materials in which the interlayer chemistry is not lost to achieve organic functionalization. The addition of organic character along with the retention of the original interlayer character produces a material with dual functionality and opens the window for many unique compounds and applications.

The surface reactivity of α- zirconium phosphate nano platelets was investigated with a variety of coupling agents. Initially, covalent attachment of molecules to the exterior surface of the nano particles was attempted with silanes and epoxides. Subsequently, the ion exchange character of the surface phosphate groups was used to deposit metal ions on the surface. The metal ion layer was then coordinated with phosphonic acid ligands to produce surface functionalized ZrP. In all cases the exclusive functionalization of the surface and covalent attachment of the reactive groups to the inorganic layer was confirmed using a combination of techniques including X-ray powder diffraction, XPS, electron microprobe, Solid State NMR, FTIR, and TGA. The viability of producing nano particles with both a controlled interior and exterior by combining the intercalation chemistry of ZrP with the newly developed surface chemistry was then investigated. Characterization of the resulting materials indicated that functionalization of intercalated ZrP was successful and an efficient procedure for the design of multifunctional nanoparticles. The control of the interlayer and surface allows for nanoparticles to be designed for particular applications. Polymer nanocomposites and a photo-induced electron transfer system were prepared using the multifunctional nanoparticles as test cases.