Mesoporous functionalized nanoparticles (nanosilica) and functionalized mixed-structure silica with surface Si-Cl groups were prepared via a SiCl4 hydrolysis base-catalyzed sol-gel process. This study presents hierarchically structured systems formed via growth and self-assembly of functionalized silica nano spheres on the surface of Sylopol-948, generating functionalized mixed-structure silica. The fabricated materials were characterized by nitrogen adsorption, small angle X-ray (SAXS), dynamic light scattering (DLS), zeta potential (ZP), infrared spectroscopy (FT-IR), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). The incorporation of Si-Cl groups (0.02-0.43 Cl/Si) on the surface-to functionalize the nanoparticles and modify their properties-was confirmed by SEM-EDX and cyclic voltammetry. In functionalized mixed-structure silica, the SBET value (567 m(2)/g) increases, particle size (13.6-17.2 nm) decreases and surface charge (-9.0 mV) diminishes as SiCl4 concentration increases. In functionalized nanosilica, a lower SiCl4 concentration results in a higher S-BET value (730.6 m(2)/g), smaller nanoparticle size (6.0-12.4 nm) and higher surface charge (-22.9 mV). These materials were experimentally compared and found to demonstrate improved characteristics compared to Stober nanosilica, non-functionalized mixed-structure silica, and Sylopol-948. (C) 2016 Published by Elsevier B.V.