In situ and ex situ preparations of ZnO/poly-{trans-[RuCl2(vpy)4]/styrene} nanocomposites

Abstract

As nanopartículas de semicondutores são de grande interesse científico e tecnológico devido ao fato das suas propriedades eletrônicas e ópticas dependerem do tamanho das partículas. Os nanocristais de semicondutores têm sido intensamente investigados, por exemplo, como nanocargas em diversas matrizes poliméricas. Neste trabalho é apresentada a síntese de nanocompósitos obtidos pela incorporação de nanocristais (NCs) de ZnO no copolímero poli-{trans-[RuCl 2 (vpy) 4 ]/sty} (sty = estireno e vpy = 4-vinilpiridina). Numa primeira etapa, o copolímero foi preparado por meio da reação entre os monômeros trans- [RuCl 2 (vpy) 4 ] e estireno. Em seguida, NCs de ZnO passivados organicamente foram misturados com o copolímero poli-{trans-[RuCl 2 (vpy) 4 ]/sty}, em CH 2 Cl 2 , para produzir filmes poliméricos do nanocompósito após evaporação do solvente (método ex situ). As propriedades destes materiais foram comparadas com as de nanocompósitos análogos obtidos a partir da polimerização in situ na presença de NCs de ZnO.Nanosized semiconductor particles are of great scientific and technological interest because of their size-dependent electronic and optical properties. Semiconductor nanocrystals have been investigated, for example, as nano-fillers for diverse polymer matrices in order to produce new optically active materials. Here we report, for the first time, results concerning the preparation of nanocomposites made of ZnO nanocrystals (NCs) incorporated in the co-polymer poly-{trans-[RuCl 2 (vpy) 4 ]/sty (sty = styrene and vpy = 4-vinylpyridine). In a first step, the co-polymer was prepared by reaction of trans-[RuCl 2 (vpy) 4 ] with styrene. Then, organically capped ZnO NCs and poly-{trans-[RuCl 2 (vpy) 4 ]/sty} were mixed in CH 2 Cl 2 to produce cast films of the nanocomposites after evaporation of the solvent (ex situ method). The properties of these materials were compared to those of nanocomposites obtained by in situ polymerization in the presence of ZnO NCs. Keywords: ruthenium(II) complexes, nanocomposites, ZnO nanocrystals IntroductionSemiconductor nanocrystals (NCs) show size-dependent optical properties and have been investigated as new optical materials in the field of nanotechnology.1 For example, these nanosized particles have been used together with polymers to produce new optically active inorganic/ polymer nanocomposites. This approach takes advantage not only of the intrinsic properties of the starting materials but might also result in new properties due to synergistic effects arising from the combination of the inorganic and organic components.2 Depending on the nanoparticles' characteristics and the synthesis/processing of the polymer matrices, there are several synthetic strategies to prepare polymer nanocomposites. Available approaches include solgel methods, 3 melt-processing 4,5 and in situ polymerization.6,7The homogeneous distribution of inorganic nanoparticles within the polymer matrix and the strong interface adhesion between the matrix and nano-fillers are important aspects to be conside...

From Ruthenium Complexes to Novel Functional Nanocomposites: Development and Perspectives

“…[68] This study allows further development of this synthetic strategy to obtain homogeneous nanocomposites of variable composition that can find practical interest in ruthenium-based sensor devices. …”

“…When incorporating the semiconductor NPs into the copolymer matrix, the properties of the initial NPs were maintained, such as optical and structural properties. [68] Scanning electron microscopy (SEM) of the nanocomposite and energy-dispersive X-ray spectroscopy (EDS), clearly demonstrate the homogeneous presence of Zn and Ru throughout the whole sample. (Figure 6).…”

SERS Research Applied to Polymer Based Nanocomposites

“…Our own investigation in this field has the focus on the preparation of such polymer based composites by in situ polymerization using distinct synthetic strategies, such as emulsion [137], suspension [138,139] and (mini)emulsion polymerization [140,141], a variant of emulsion polymerization. In the latter, the emulsions are nanosized and organically capped NPs can be allocated in the interior of the hydrophobic monomer droplets [142,143].…”

Chapter 9. Nano dimensional ZnO: new chemical insights from an old material

“…[110][111][112][113] The preparation of metal/ZnO nanocomposites may have a widespread range in applications, such as the enhancement of gas sensing properties, 114 photocatalytic and photoelectrochemical applications 102 or as an antimicrobial agent in packaging. 98 Another example is its use as a cholesterol biosensor described by Wang et al 101 The authors created a novel scheme for the fabrication of Pt-Au functionalized ZnO nanorods (Pt-Au@ZnO NRs) and multi-walled carbon nanotubes (MWCNTs) modified electrodes and subsequently develop these hybrid structures for cholesterol biosensing.…”