Effect of both protective and reducing agents in the synthesis of multicolor silver nanoparticles

Abstract

In this paper, the influence of variable molar ratios between reducing and loading agents (1:100, 1:50, 1:20, 1:10, 1:5, 1:2, 1:1, 2:1) and between protective and loading agents (0.3:1, 0.75:1, 1.5:1, 3:1, 7.5:1, 30:1, 75:1) in the synthesis of silver nanoparticles by chemical reduction has been evaluated to obtain multicolor nanoparticles with a high stability in time. The protective agent poly(acrylic acid, sodium salt) (PAA) and reducing agent dimethylaminoborane (DMAB) play a key role in the formation of the resultant color. Evolution of the optical absorption bands of the silver nanoparticles as a function of PAA and DMAB molar ratios made it possible to confirm the presence of silver nanoparticles or clusters with a specific shape. The results reveal that a wide range of colors (violet, blue, green, brown, yellow, red, orange), sizes (from nanometer to micrometer), and shapes (cubic, rod, triangle, hexagonal, spherical) can be perfectly tuned by means of a fine control of the PAA and DMAB molar concentrations.

Systematic investigation on hydrazine hydrate assisted reduction of silver nanoparticles and its antibacterial properties

“…For 3 mM of AgNO 3 , well resolved surface plasmon resonance peak at 413 nm is attributed to the formation of good quality of silver nanoparticles. At higher concentration (4 mM), multi peak is observed with the resulting change in colour (dark brown) (inset image ofFigure 2a) with the resolved maximum absorption peak at 656 nm that may be due to the mixture of morphological features of silver nanoparticles which correlates with the result of Rivero et al[22,23] The interesting tunable and controlled formation of different structures of metal nanoparticles is of great interest in simple solution based production of colloidal metal nanoparticles. In this connection, we made attempt for the production of different structures of silver nanoparticles by tuning the stabilizing and reducing agent concentration.…”

Design of Nanostructured Functional Coatings by Using Wet-Chemistry Methods

“…In this sense, one of the most relevant aspects of the synthesis of metallic nanoparticles, mostly silver (AgNPs) or gold nanoparticles (AuNPs), is that there is a high dependence between their optical properties (color formation) and the resultant morphology (shape and size). The possibility of monitoring the evolution of the LSPR wavelength position by UV-Vis measurements and the corresponding color formation makes possible the design of metallic nanoparticles with a specific shape and size [129]. An illustrative example can be observed in Figure 12 where a multicolor silver map (Figure 12a) is presented as a function of a strict control of both protective (polyacrylic acid sodium salt, PAA) and reducing (dimethylamino borane, DMAB) agents during the synthesis process by using a chemical reduction method for a fixed molar concentration of the loading agent (silver nitrate, AgNO 3 ).…”

Localized Surface Plasmon Resonance for Optical Fiber-Sensing Applications

“…Other important advantage is that these polyelectrolytes can be used as protective agents of the metal nanoparticles. The encapsulating agent plays an important role for the synthesis of nanoparticles with a specific morphology because it limits the growth of the particles, directs their shape and provides colloidal stability [18]. Due to this, several works have been focused on the fabrication of thin films based on the incorporation of different shaped gold and silver nanoparticles using several types of polyelectrolytes [30][31][32].…”

“…In addition, an adequate protective agent is also used because it plays a dual role of preventing the agglomeration and maintaining the unaltered aggregation state of the metal nanoparticles. In this sense, Rivero et al [18] presented a multicolor silver map with a long-term stability by means of a fine control of the molar ratio between both protective agent (polyacrylate, PAA) and reducing agent (dimethylaminoborane, DMAB), enabling a wide range of colors (yellow, orange, red, violet, blue, green, brown) and tunable shape and size. Figure 2a shows a multicolor silver map, which is formed by 56 different combinations of protective agent concentration and reducing/loading agent ratio.…”