Fractal aggregation and optical absorption of copper nanoparticles prepared by in situ chemical reduction within a Cu2+-polymer complex

1999 ◽  
Vol 74 (12) ◽  
pp. 1692-1694 ◽  
Author(s):  
C. Huang ◽  
C. Z. Yang
2003 ◽  
Vol 789 ◽  
Author(s):  
Cheng Huang ◽  
Gang Huang ◽  
C. Z. Yang

ABSTRACTResearch on nanocrystalline materials and the physics behind their properties have attracted considerable attention. A number of physical and chemical techniques have been used to synthesize different nanomaterials and nanocomposites. Optical absorption characteristics of composites containing nanosized metals or semiconductors have been investigated for potential applications in nonlinear optics and photonic crystals and also to understand the effect of particle size on the band gap of the material concerned. These materials show a large third-order nonlinear susceptibility. A polymer-matrix nanocomposite containing copper particles has been prepared by in situ chemical reduction within a polymer-metal complex solid film. The copper particle size in the order of 10 nm is controlled by the initial content of the metal ions in the complex. Their fractal pattern and the value of the fractal dimension indicate that there exists a cluster-cluster aggregation (CCA) process in the present system. Optical absorption spectra of copper-polymer nanocomposites show distinct plasma absorption bands and quantum size effect in the samples. More studies on optical properties of composites containing nanosized metals are within the Drudeframe on the basis of Mie theory, but the electrons behave in a wavelike rather than a particlelike way as the particle size decreases to below 10 nm, and the classical Drude model should be modified considering the quantum confinement effect. In this paper, the calculated blueshift of the resonance peak based on a quantum-sphere model (QSM) proposed by Huang and Lue, gives remarkable agreement with the experimental data as the size of copper particles embedded in the polymer becomes smaller.


2018 ◽  
Vol 27 (2) ◽  
pp. 33
Author(s):  
R. Salazar R. ◽  
M. Aquino ◽  
Y. Alvarez

Agentes capaces de transmitir enfermedades como las bacterias, virus y hongos son los principales causantes de las infecciones intrahospitalarias (IIH) en el mundo, esto ha motivado el desarrollo de los Nuevos Materiales basados en la Nanotecnología, donde en una rama de este se sintetizan nanocompósitos antibacteriales del tipo: Polímero/Metal Antibacterial, sintetizando superficies con gran actividad inhibidora de bacterias. En el presente trabajo, se han generado nanocompósitos poliméricos antibacteriales, preparando el Policloruro de Vinilo (PVC) de resina en emulsión como plastisol y sintetizando nanopartículas de Cobre dentro de la matriz polimérica (in‐situ). La descripción de la metodología se da con la síntesis de un precursor de Cobre para posterior dispersión mediante pulsos ultrasónicos, posterior estabilización y mezclado con los aditivos del PVC para posterior reducción química durante el gelificado de los plastisoles. El análisis espectral de los laminados de PVC/NPsCu0 por medio de Fluorescencia de Rayos X en Energía Dispersiva (FRX‐ED), utilizando el software específico PyMca 4.7.4, revelan que la importancia del tiempo de gelificación del PVC guarda relación con el grado de reducción del Ácido Ascórbico (AA) sobre el Cu2+. Por otro lado, resultados del análisis por Espectroscopia Electrónica de Barrido (MEB) revelan que las dimensiones de las NPsCu0 varían en un rango de 50 a 250 nm. Los patrones de difracción de Rayos X (DR‐X) evidencian la parcial cristalización polimérica del PVC y la presencia de Cu0. Se confirmó la actividad antibacteriana de los laminados de PVC/NPsCu0 por el método de difusión de disco sobre Eschericcia coli O157:H7; el halo de inhibición promedio resultó ser de 9,7 mm que implica un significativo efecto bactericida sobre la cepa mencionada. La viabilidad del desarrollo de estos nanocompósitos poliméricos se estudió por medio de un ensayo nanotoxicológico mediante el análisis citotóxico de los nanocompósitos de PVC/NPsCu0 en células de sangre periférica humana, concluyendo que dicho efecto citotóxico sobre células sanas es menor al 8%. La viabilidad del desarrollo de estos nanocompósitos poliméricos se estudió por medio de un ensayo nanotoxicológico mediante el análisis citotóxico de los nanocompósitos de PVC/NPsCu0 en células de sangre periférica humana, concluyendo que dicho efecto citotóxico sobre células sanas es menor al 8%. Palabras clave.- PVC, infecciones intrahospitalarias, nanocompósitos, nanopartículas de cobre. ABSTRACT Disease transmitting microorganisms, such as bacteria, viruses and fungi, are the main causes of hospital‐acquired infections (HAI). This is the justification for the development of nanotechnology‐based new materials and, in particular, for the synthesis of antibacterial nanocomposites of the type polymer / antibacterial metal, which create surfaces with a large bacteria inhibiting activity. In the present work, antibacterial polymeric nanocomposites have been created by preparing polyvinyl chloride (PVC) from a resin emulsion as plastisol and synthesizing copper nanoparticles in‐situ within the polymer matrix. The methodology of the process includes the synthesis of a copper precursor, its dispersion by ultrasonic pulses, its stabilization and mixing with other PVC additives, in order to obtain chemical reduction during the gelation of the plastisols. Analysis of the PVC / NPsCu0 laminates by Energy Dispersive X‐ray Fluorescence (EDXRF), using the PyMca software 4.7.4, reveals that the importance of the PVC gelation time is related to the degree of reduction of ascorbic acid (AA) on Cu2 +. On the other hand, examination by Scanning Electron Microscopy (SEM) shows that the size of the NPsCu0 varies between 50 and 250 nm. Examination by X‐ray Diffraction (XRD) shows the partial polymer crystallization of PVC and the presence of Cu0. The antibacterial activity of the PVC / NPsCu0 laminates was confirmed by the disc diffusion method on Escherichia coli O157: H7; the average zone of inhibition was 9.7 mm, indicating a significant bactericidal effect on this strain. A nanotoxicological assay was carried out to evaluate the viability of the development of these polymeric nanocomposites. The cytotoxic analysis of the PVC / NPsCu0 nanocomposites in human peripheral blood cells concluded that the cytotoxic effect on healthy cells was less than 8%. Keywords.- PVC, hospital‐acquired infections, nanocomposites, copper nanoparticles


2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Ernesto Beltrán-Partida ◽  
Benjamín Valdez-Salas ◽  
Ernesto Valdez-Salas ◽  
Guillermo Pérez-Cortéz ◽  
Nicola Nedev

The design route, synthesis, and characterization of spherical copper nanoparticles with antifungal potential are reported in the present work. Copper nanoparticles were synthesized by a novel, inexpensive, and eco-friendly chemical reduction method using ascorbic acid as a reductant and stabilizer under reflux conditions. The characterization results showed the formation of homogeneous, dispersed, and stable spherical ascorbic acid-capped copper nanoparticles (CuNPs) with a diameter of 250 nm. The CuNPs exhibited sustained antifungal activity againstCandida albicans(C. albicans) after 24 h and even 48 h of incubation. Using enhanced dark-field microscopy, we presented the in situ interaction between CuNPs andC. albicans. Here, part of the interaction of CuNPs among theC. albicans, studied without the use of any chemical and/or physical fixing method, is discussed. The results indicate that part of the antifungal mechanism involves a promoted adhesion of CuNPs onto the cell wall and a massive accumulation of CuNPs into the fungal cells, concluding in cellular leakage. The cytotoxicity (viability) evaluations indicated that our CuNPs were more biocompatible after comparison to the Cu precursor and triclosan (a commercial antifungal drug). The synthesized CuNPs will open up a new road for their possible use as a potent antimicrobial agent for clinical and industrial applications.


Author(s):  
Ain Uddin ◽  
Weifan Sang ◽  
Yong Gao ◽  
Kyle Plunkett

The synthesis of poly(p-xylylene)s (PPXs) with sidechains containing alkyl bromide functionality, and their post-polymer modification, is described. The PPXs were prepared by a diimide hydrogenation of poly(p-phenylene vinylene)s (PPVs) that were originally synthesized by a Gilch polymerization. The polymer backbone reduction was carried out with hydrazine hydrate in toluene at 80 °C to provide polymers with the sidechain-containing bromide functionality intact. To demonstrate post-polymer modification of the sidechains, the resulting PPX polymers were modified with trimethylamine to form tetraalkylammonium ion functionality and were evaluated as anion conducting membranes. While PPX homopolymers containing tetralkylammonium ions were completely water soluble and not able to form valuable films, PPX copolymers containing mixed tetraalkylammonium ions and hydrophobic chains were capable of film formation and alkaline stability. In addition, an in situ crosslinking process that used N,N,N',N'-tetramethyl-1,6-hexanediamine during the tetraalkylammonium formation of brominated PPX polymers was also evaluated and gave reasonable films with conductivities of ~10 mS-cm-1.


2019 ◽  
Author(s):  
Ain Uddin ◽  
Weifan Sang ◽  
Yong Gao ◽  
Kyle Plunkett

The synthesis of poly(p-xylylene)s (PPXs) with sidechains containing alkyl bromide functionality, and their post-polymer modification, is described. The PPXs were prepared by a diimide hydrogenation of poly(p-phenylene vinylene)s (PPVs) that were originally synthesized by a Gilch polymerization. The polymer backbone reduction was carried out with hydrazine hydrate in toluene at 80 °C to provide polymers with the sidechain-containing bromide functionality intact. To demonstrate post-polymer modification of the sidechains, the resulting PPX polymers were modified with trimethylamine to form tetraalkylammonium ion functionality and were evaluated as anion conducting membranes. While PPX homopolymers containing tetralkylammonium ions were completely water soluble and not able to form valuable films, PPX copolymers containing mixed tetraalkylammonium ions and hydrophobic chains were capable of film formation and alkaline stability. In addition, an in situ crosslinking process that used N,N,N',N'-tetramethyl-1,6-hexanediamine during the tetraalkylammonium formation of brominated PPX polymers was also evaluated and gave reasonable films with conductivities of ~10 mS-cm-1.


Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 401
Author(s):  
Ignacio A. Jessop ◽  
Yasmín P. Pérez ◽  
Andrea Jachura ◽  
Hipólito Nuñez ◽  
Cesar Saldías ◽  
...  

In the search for new materials to fight against antibiotic-resistant bacteria, a hybrid composite from metallic copper nanoparticles (CuNPs) and a novel cationic π-conjugated polyelectrolyte (CPE) were designed, synthesized, and characterized. The CuNPs were prepared by chemical reduction in the presence of CPE, which acts as a stabilizing agent. Spectroscopic analysis and electron microscopy showed the distinctive band of the metallic CuNP surface plasmon and their random distribution on the CPE laminar surface, respectively. Theoretical calculations on CuNP/CPE deposits suggest that the interaction between both materials occurs through polyelectrolyte side chains, with a small contribution of its backbone electron density. The CuNP/CPE composite showed antibacterial activity against Gram-positive (Staphylococcus aureus and Enterococcus faecalis) and Gram-negative (Escherichia coli and Salmonella enteritidis) bacteria, mainly attributed to the CuNPs’ effect and, to a lesser extent, to the cationic CPE.


2021 ◽  
pp. 004051752199547
Author(s):  
Min Hou ◽  
Xinghua Hong ◽  
Yanjun Tang ◽  
Zimin Jin ◽  
Chengyan Zhu ◽  
...  

Functionalized knitted fabric, as a kind of flexible, wearable, and waterproof material capable of conductivity, sensitivity and outstanding hydrophobicity, is valuable for multi-field applications. Herein, the reduced graphene oxide (RGO)-coated knitted fabric (polyester/spandex blended) is prepared, which involves the use of graphite oxide (GO) by modified Hummers method and in-situ chemical reduction with hydrazine hydrate. The treated fabric exhibits a high electrical conductivity (202.09 S/cm) and an outstanding hydrophobicity (140°). The outstanding hydrophobicity is associated with the morphology of the fabric and fiber with reference to pseudo-infiltration. These properties can withstand repeated bending and washing without serious deterioration, maintaining good electrical conductivity (35.70 S/cm) and contact angle (119.39°) after eight standard washing cycles. The material, which has RGO architecture and continuous loop mesh structure, can find wide use in smart garment applications.


2021 ◽  
Vol 35 (7) ◽  
pp. 6250-6264
Author(s):  
Kai Fang ◽  
Liujia Ma ◽  
Ya-Jun Cheng ◽  
Senlin Xia ◽  
Zhaohui Yang ◽  
...  

2015 ◽  
Vol 33 (3) ◽  
pp. 627-634 ◽  
Author(s):  
Zahoor H. Farooqi ◽  
Zonarah Butt ◽  
Robina Begum ◽  
Shanza Rhauf Khan ◽  
Ahsan Sharif ◽  
...  

Abstract Poly(N-isopropylacrylamide-co-methacrylic acid) microgels [p(NIPAM-co-MAAc)] were synthesized by precipitation polymerization of N-isopropylacrylamide and methacrylic acid in aqueous medium. These microgels were characterized by dynamic light scattering and Fourier transform infrared spectroscopy. These microgels were used as micro-reactors for in situ synthesis of copper nanoparticles using sodium borohydride (NaBH4) as reducing agent. The hybrid microgels were used as catalysts for the reduction of nitrobenzene in aqueous media. The reaction was performed with different concentrations of cat­alyst and reducing agent. A linear relationship was found between apparent rate constant (kapp) and amount of catalyst. When the amount of catalyst was increased from 0.13 to 0.76 mg/mL then kapp was increased from 0.03 to 0.14 min-1. Activation parameters were also determined by performing reaction at two different temperatures. The catalytic process has been discussed in terms of energy of activation, enthalpy of activation and entropy of activation. The synthesized particles were found to be stable even after 14 weeks and showed catalytic activity for the reduction of nitrobenzene.


Sign in / Sign up

Export Citation Format

Share Document