Synthesis of Ag-PVA and Ag-PVA/PET-s20 composites by supercritical CO2 method and study of silver nanoparticle growth

Abstract

CO 2 supercrítico foi utilizado para preparar compósitos poliméricos com prata, prata/poli álcool vinílico e prata/ poli álcool vinílico/ poli (tereftalato de etileno) sulfonado, pela impregnação de um precursor de prata nas matrizes poliméricas no estado sólido seguida da redução térmica do precursor. Difração de raio X, microscopia eletrônica de varredura, espectroscopia de energia dispersiva, microscopia de força atômica, análise termogravimétrica e espectroscopia no UV/vis dos compósitos indicaram que as condições de preparação e a composição da matriz polimérica influenciam o tamanho e a forma das partículas de prata formadas, assim como, a uniformidade e a distribuição das partículas nas matrizes poliméricas. As partículas de prata nos compósitos ricos em PVA são menores, possuem formas mais uniformes e apresentam distribuição de tamanho mais estreita do que nos compósitos ricos em PETs.Supercritical CO 2 has been used to prepare silver polymer composites, silver/poly(vinyl alcohol) and silver/poly(vinyl alcohol)/sulfonated poly(ethylene terephthalate) through impregnation of a silver precursor in solid-state polymeric matrices followed by thermal reduction of the silver precursor. X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, atomic force microscopy, thermogravimetric analysis and UV/vis spectroscopy indicate that synthesis conditions and polymeric matrix composition affect silver particle size, shape and distribution in polymeric matrices. Silver particles are smaller, have a more uniform shape and present narrower size distribution in PVA-rich than in PETs-rich composites.Keywords: composites, polymers, surfaces, crystal growth, electron microscopy Introduction Nanostructured silver particles in zero oxidation state have been object of great interest for decades due to their use in catalysis, photography, photonics, electronics, information storage, labeling, imaging, sensing, and surface-enhanced Raman scattering (SERS). [1][2][3][4][5][6] In the several works with different preparation methods reported, the silver precursor, a silver salt, is reduced in solution in the presence of a capping agent. [7][8][9][10][11][12][13][14] The polyol process has been known for decades as a generic route for the synthesis of metal colloids. [12][13][14] It concerns the preparation of metallic powders, essentially of cobalt, nickel, copper, and precious metals, by reduction of inorganic compounds in liquid polyol, which acts both as a solvent and a reducing agent, as stated by Blin et al. 15 In recent works on the polyol reaction mechanism, Shengming et al. 16,17 showed that polyol is oxidized during the process and produces CO 2 molecules, which are detected as carbonate ions.Recently, supercritical fluids have been applied to obtaining new materials. 18 Supercritical state has been studied and reported in literature since its discovery in the early 19th century by Baron La Tour. 19 Supercritical fluids allow controlling particle shape and size to produce highly uniform nanometri...

Copper nanoparticles stabilized by reduced graphene oxide for CO2 reduction reaction

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