Characterization of in situ prepared nanocomposites of PS and TIO₂ nanoparticles surface modified with alkyl gallates: Effect of alkyl chain length

Abstract

Incorporation of surface modified TiO2 nanoparticles into polystyrene (PS) matrix was achieved by in situ bulk radical polymerization of styrene. The surface of TiO2 nanoparticles was modified with four amphiphilic esters of the gallic acid (octyl, decyl, lauryl and cetyl gallate), which have different lengths of hydrophobic alkyl chain (C8–C16). FTIR and UV‐Vis spectroscopy measurements confirmed the formation of a charge transfer complex between surface Ti atoms and gallic esters. Microstructural characterization of the synthesized nanocomposites revealed that the best dispersion of TiO2 nanoparticles in PS was achieved when the TiO2 surface was modified with octyl gallate. The presence of surface modified TiO2 nanoparticles by different alkyl gallates does not have an influence on the molecular weight and glass transition temperature of PS matrix. On the other hand, thermal and thermo‐oxidative stability of PS were significantly improved by incorporation of surface modified TiO2 nanoparticles. The most pronounced improvement of thermal and thermo‐oxidative stability was observed for TiO2 nanoparticles surface modified with octyl gallate. POLYM. COMPOS., 2013. © 2013 Society of Plastics Engineers

Synthesis and characterization of the surface modified titanium dioxide/epoxy nanocomposites

“…The absorption of the surface modified TiO 2 nanoparticles starts at around 650 nm and the absorption of aqueous TiO 2 starts at around 380 nm. This significant shift of the absorption spectra indicates the reaction of gallic acid esters with surface Ti atoms of nanoparticles and the formation of CTC [26,30]. However, the obtained results revealed that the hydrophobic part length of gallates used for the surface modification of TiO 2 nanoparticles had no significant influence on the position of the absorption spectra of TiO 2 nanoparticles.…”

“…Aromatic ligands with two or three adjacent phenolic OH groups (catechol, pyrogallol and gallic acid) can be adsorbed on the surface of TiO 2 by forming chelating or bridging complexes with titanium ions on the surface [24][25]. In our previous works, TiO 2 nanoparticles were surface modified with different alkyl gallates [26] and then incorporated into the poly(methyl mehacrylate) and epoxy matrix [27]. The length of the aliphatic part of the used gallates showed a great effect on dispersability of the surface modified TiO 2 nanoparticles and on the properties of both matrices.…”

Solution processable TiO2 nanoparticles capped with lauryl gallate

“…The addition of inorganic oxide nanoparticles permits the adjustment of different characteristics of organic polymers, like thermal stability, optical, mechanical and/or electrical properties [5,9,10]. Composites containing TiO 2 nanoparticles dispersed in a polymeric matrix have a wide range of applications, i.e., food packaging materials with biocidal and photodegradability properties [11], the dielectric material of capacitors and thin films transistors [12,13], high refractive index coatings [10] and visible transparent UV-filters [14].…”

Impact of titanium and silica/titanium fumed oxide nanofillers on the elastic properties and thermal decomposition of a polyester resin

“…Both titanium and silicon dioxide nanosized particles have been widely used to extend the functional characteristics of polymer composites . For example, the embedding of titanium dioxide (TiO 2 ) nanoparticles into thermosetting polymers and elastomers results in enhancements in their thermal resistance, stiffness and toughness, thermal conductivity, tensile properties, impact strength, and fracture toughness . It is remarkable that the aforementioned improvements manifest themselves at low filler contents (≤5 wt %) and are related to the stabilization of the polymer's inner structure because of the binding of macromolecular chains to the superficial centers of the particles …”