Surface modification of alumina nanoparticles with silane coupling agents

Abstract

No presente trabalho nós descrevemos a modificação da superfície de nanopartículas de alumina utilizando alcoxissilanos possuindo grupos epóxi (agentes de acoplamento baseados em silano, SCA). Os materiais foram caracterizados por espectroscopia de infravermelho e ressonância magnética nuclear de estado sólido. Considerando-se que as nanopartículas de alumina podem ser modificadas com SCA, como evidenciado por 13 C CPMAS RMN, a presença de grupos arilsulfonato na superfície da alumina promoveu a polimerização pelo mecanismo de abertura do anel epóxido, a qual facilitou a modificação da superfície de alumina pela SCA. Os resultados de difratometria de raios X de pó e 27 Al MAS RMN mostraram claramente que o processo de polimerização SCA e a modificação da superfície, não provocaram mudanças estruturais, nem transições de fase na alumina. A modificação da superfície causou uma diminuição na estabilidade térmica do material resultante em relação às nanopartículas de alumina pura.In the present paper we describe the surface modification of alumina nanoparticles using epoxy-containing alkoxysilanes (silane coupling agents, SCA). The materials were characterized using infrared spectroscopy and solid-state nuclear magnetic resonance. Whereas, neat alumina nanoparticles could be expectedly modified with the afore mentioned SCA, as evidenced by 13 C CPMAS NMR, the presence of arylsulphonates at the surface of alumina caused the ringopening polymerization of the epoxide. This polymerization reaction facilitated the surface modification of alumina by the SCA. X-ray powder diffraction and 27 Al MAS NMR clearly demonstrated that in spite of the SCA polymerization, there were neither structural changes nor phase transitions in the alumina after the surface modification. The surface modification decreased the thermal stability of alumina, in comparison to pristine alumina nanoparticles.Keywords: alumina, surface functionalization, structure-properties relationship, thermal stability IntroductionAlumina and other oxides are widely found in many applications including support for catalysts, 1 organometallic 2 (including metal carbonyl clusters), 3 metal-organic 4 and luminescent compounds, 5 formulations for dental applications, 6 additives for polymer (nano)composites, 7 ceramic membranes, 8 pre-concentration reactors 9 and stationary phases for chromatography 10 to name a few.When dealing with multi-component systems, the interface plays a decisive role on dispersion and adhesion between the continuous phase (matrix) and the additives (fillers). 11 Therefore, the surface properties of metal oxides (including alumina) have to be tailored in order to improve the filler-matrix adhesion. 12 Alumina can be modified by carboxylates, sulfonates and fosfonates 13 to incorporate hydrophobic (or hydrofilic character) and functional groups (e.g. amines), but silane coupling agents and other siloxane precursors have been most extensively used to modify the surface of alumina for different purposes. 4,7,8,11,14 Silylated alumina can improv...

A review of current coupling agents for modification of metal oxide nanoparticles

“…Prado et al [92] treated the alumina NPs surface with [2-(3,4 epoxycyclohexyl)ethyl]trimethoxysilane (Fig. 16).…”

Surface Modification of Alumina Nanoparticles: A Dispersion Study in Organic Media

“…The surface modification decreased the thermal stability of alumina, in comparison with pristine alumina NPs. 16 The surface of Al 2 O 3 NPs was modified using vinyltrimethoxysilane (VTMS) layer. Analyses revealed that the silane coupling successfully adsorbed on the surface of nano Al 2 O 3 via chemical interaction.…”

Enhanced Fluorescent DNA Microarray Using an Optical Interference Mirror Slide

“…1. OIM slides were firstly aminated by incubation in 1% APTMS diluted with H 2 O for 1.5 h at room temperature, (20,24) washed in H 2 O for 10 min, and then dried in an oven for 10 min at 110 °C. All experiments reported in this section were performed at room temperature.…”