Formation of Stable Paramagnetic Nanocomposites Containing Zero-Valence Silver and Copper in a Polymeric Matrix

Abstract

Magnetic properties of perspective nanocomposite materials based on copolymers of 1-vinyl-1,2,4-triazole with acrylonitrile and the formation of zero-valence metallic magnetic nanoparticles were investigated by electron paramagnetic resonance (EPR). In the EPR spectra of the nanocomposites intensive narrow singlets of conducting electrons with g = 2.00 were observed. The shape and width of the signals for silver and copper particles of the nanocomposites depended on microwave power. The Curie law character of the temperature dependences of intensity, g-factor value, and width of silver and copper nanoparticles' signals were determined. Paramagnetic properties of the nanocomposites were found to remain constant over a long amount of time. X-ray diffraction (XRD), scanning electron microscope (SEM), teraohmmeter measurements, and atomic absorption analysis were also used to characterize these nanocomposites. The formation of the silver and copper nanoparticles from the rise of small clusters and their growth up to stabilization within the matrix under thermoreduction of initial complexes was monitored by EPR.

Ligand Binding to Copper Nanocrystals: Amines and Carboxylic Acids and the Role of Surface Oxides

“…These numbers are about 3 times larger than the corresponding resonances in the case of semiconductor NCs, such as CdSe (see Supporting Information S2). Possibly, this line broadening results from a different magnetic environment experienced by OlNH 2 when bound to Cu NCs, in agreement with previous reports on paramagnetism in Cu NCs …”

“…Possibly, this line broadening results from a different magnetic environment experienced by OlNH 2 when bound to Cu NCs, in agreement with previous reports on paramagnetism in Cu NCs. 27 Despite the pronounced line broadening, the alkene proton resonance 4 remains well resolved, and based on its integrated intensity, we estimated that the sample analyzed here has a surface concentration of bound OlNH 2 of 1.4 nm −2 . As compared to semiconductor NCs, which often have ligand surface concentrations in the range 3.0−5.0 nm −2 , this number is rather low.…”

Strong stabilisation properties of humic substance matrixes for silver bionanocomposites

“…Based upon the EPR characteristics, it can be concluded that the narrow line is a superposition of signals caused by free radicals of the initial matrix and zero-valence silver nanoparticles. This is in good agreement with the EPR data for conductivity electrons of zero-valence metal particles in the nanosystems (such singlets are inherent in the nanoparticles within the range between 1 and 30 nm [24][25][26]). The reduction of silver to zero-valence state most likely occurs due to the oxidable aldehyde and phenol groups [11,12], which are contained in HS in significant amounts.…”

Nontoxic hydrophilic polymeric nanocomposites containing silver nanoparticles with strong antimicrobial activity

“…Recently, it has been found that polymers of 1-vinyl-1,2,4-triazole represent a highly effective polymeric stabilizing matrix for metallic nanoparticles, and the nanocomposites obtained show properties of polymer and metal counterparts (hydrophilicity, complex formation ability, chemical thermal stability, biological activity, etc). [4][5][6][7] Also, it has been demonstrated 8 that polymer nanocomposites containing silver nanoparticles (AgNPs) in the poly-1-vinyl-1,2,4-triazole matrix exert antimicrobial activity against Gram-positive and -negative museum and hospital strains, nonfermenting bacteria, and fungi.…”