Controlling the Hydrophobicity of Submicrometer Silica Spheres via Surface Modification for Nanocomposite Applications

Abstract

We control the hydrophobicity of submicrometer silica spheres by modifying their surface with -CH3, -CH=CH2, -(CH2)(2)CH3, -CH2(CH2)(4)CH2-, -C(6)H(5), -(CH2)(7)CH3, and -(CH2)(11)CH3 groups through a modified one-step process. The scanning electron microscopy (SEM), quasi-elastic light scattering (QELS), UV-visible spectra, nitrogen sorption, and water vapor adsorption methods are used to characterize the particles. The SEM micrographs of the particles demonstrate that the modified particles are uniformly spherical, monodisperse, and well-shaped with the particle size ranging from 130 to 149 nm depending on the modified organic groups. In aqueous solution, the particles modified with phenyl groups have an obvious UV absorption peak at around 210 nm, whereas the other modified particles and unmodified particles do not have any UV-visible absorption peaks. There exist obvious differences in the amount of water vapor adsorbed depending on the type of surface functional groups of the modified particles. Compared with the unmodified particles, the modified particles have a lower water vapor adsorption because of the improved hydrophobicity of the particle surface. As a potential application, we prepared polystyrene/SiO2 nanocomposites by blending polystyrene with the synthesized particles. Water contact angle measurements show that the surface of the composite prepared with the modified particles are more hydrophobic. Confocal microscopy demonstrates that the particles are less agglomerated in the nanocomposite as the particles become more hydrophobic. These comprehensive experimental results demonstrate that the hydrophobicity of the particles can be easily controlled by surface modification with different organosilanes through a modified one-step process.

One-step synthesis of highly monodisperse hybrid silica spheres in aqueous solution

“…Although the VTES/water solution was turbid at the beginning of the stage, it appeared transparently after ∼2 h vigorous magnetic stirring. The VTES hydrolyzed in the process and released ethanol which could help the VTES to be completely dissolved in water medium [10,14]. In the presence of ammonia the supersaturation S achieved sufficiently high.…”

“…Organic-inorganic hybrid materials are used in the biocatalyst [3][4][5], the surface modification [6][7][8], and the graft [9][10][11][12][13]. In the organic-inorganic hybrid materials, synthesis of the monodisperse surface-modified silica spheres is widely studied for their modified functionalities [14,15] and extensive applications in photonic crystals [16][17][18][19]. During the synthesis, the starting mixtures often include different triethoxysilanes (RTES) or trimethoxysilanes (RTMS), where the organic substitute R was varied from methyl, phenyl, octyl to vinyl [7,14,20].…”

“…In the organic-inorganic hybrid materials, synthesis of the monodisperse surface-modified silica spheres is widely studied for their modified functionalities [14,15] and extensive applications in photonic crystals [16][17][18][19]. During the synthesis, the starting mixtures often include different triethoxysilanes (RTES) or trimethoxysilanes (RTMS), where the organic substitute R was varied from methyl, phenyl, octyl to vinyl [7,14,20]. In the procedures, monodisperse pure silica spheres which synthesized by tetraethyl orthosilicate (TEOS) (Stöber method) [21], are used as a substrate material in reaction mixture, e.g.…”

“…The procedures need two or even more inconvenient processes [3][4][5][14][15][16][17][18]. It leads to two main problems that the monodispersity and particle size could not be controlled easily.…”

Grafting of amphiphilic polymers containing quaternary ammonium group on SiO2 surface via surface-initiated ATRP

“…Among the numerous reported examples of inorganic/organic hybrid nanoparticles, silica/polymer hybrid nanoparticles have been extensively studied [18][19][20][21]. Despite the increasing studies on silica/polymer hybrid nanoparticles, they all have the specific applications owing to the hydrophobic property of the polymers deposited on the silica surface, such as polystyrene [22,23], poly (methyl methacrylate) [24][25][26], and so on. However, due to the ease of the synthesis and the particular properties, such as heat resistance, mechanical performance [27][28][29], silica nanoparticles can be applied in highway, bridge, railway, and any other areas.…”