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Click Reaction Functionalization of Hydroxylated Nanoparticles by Cyclic Azasilanes for Colloidal Stability in Oilfield Applications

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Document pages: 14 pages

Abstract: The growing interest in functionalized nanoparticlesand their implementation in oilfield applications(e.g., drilling fluids and enhanced oil recovery (EOR)) facilitate the ongoing efforts to improve their chemicalfunctionalization performance in stabilization of water based or hydrocarbonbased nanofluids. Cyclic azasilanes (CAS), substituted1-aza-2-silacyclopentanes, possess a strained 5-member ring structure. AdjacentSi and N atoms in the ring provide opportunity for highly efficient covalentsurface functionalization of hydroxylated nanoparticles through a catalyst-freeand byproduct-free click reaction. In thiswork, hydroxylated silica, alumina, diamond, and carbon coated ironcore-shell nanoparticles have been studied for monolayer CAS functionalization. Two cyclic azasilanes withdifferent R groups at N atom, such as methyl (CAS-1) and aminoethyl(CAS-2), have been utilized to functionalizenanoparticles. All reactions were found to readily proceed under mildconditions (room temperature, ambient pressure) during 1 - 2 hours ofsonication. CAS functionalized adducts of hydroxylated nanoparticles have beenisolated and their microstructure, composition, solubility and thermal stability havebeen characterized. As a result, it has been demonstrated, for the first time,that covalent surface modification with cyclic azasilanes can be extendedbeyond the previously known porous silicon structures to hydroxylated silica,alumina and carbon nanoparticles. The developed methodology was also shown toprovide access to the nanoparticles with the hydrophilic or hydrophobic surfacefunctional groups needed to enable oilfield applications (e.g., EOR, tracers,drilling fluids) that require stable water based or hydrocarbon based colloidalsystems.

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