HW analyzed the results and wrote the manuscript. ZW fabricated the InGaN thin films. CC helped to grow and measure the heterostructures. CL supervised the overall study. All authors read and approved the final manuscript.”
“Background Metal nanoparticles (NPs) (e.g., Ag, Au, Cu NPs) have attracted great interest in a number of disciplines because of their potential Wortmannin solubility dmso applications in optical, medical, or electronic Selleck MS 275 devices. The control of their size and shape is a challenging goal, and a large number of reports have been published for the preparation of metal nanoparticles of various morphologies [1–5], mainly for plasmonic
and sensing applications [6]. Very recently, our group has incorporated silver nanoparticles (AgNPs) in polymeric films for detecting fast changes of humidity (human breathing) [7, 8] and, at the same time, preventing the growth of bacteria very likely in high-humidity atmosphere [9–11]. One of the most frequently used methods is the production of AgNPs from aqueous solutions of Ag+ salts by exposure to radiation (ambient light, UV–vis, gamma) [12–15] or via chemical reduction [16, 17]. JSH-23 cost A wide number of
solvents and encapsulating agents have been used to produce AgNPs and prevent their agglomeration [18–21]. However, the addition of water-soluble polymers such as poly(acrylic acid, sodium salt) (PAA) made possible a better control of the particle growth. This polymer in aqueous solution produces polyacrylate anions (PA−) with uncoordinated carboxylate groups which
can bind metallic cations such as silver (Ag+ salts), forming intermediate charged clusters [22, 23]. Due to this, PAA is of special interest because it can control and stabilize both silver nanoparticles and clusters along the polymeric chains with a high stability in time. Several groups of investigation have carried out experiments to report the composition and evolution of these positively charged clusters [24–26]. One of the most relevant aspects of the synthesis of AgNPs is that their optical properties (the resultant color) present high dependence GNAT2 on their crystal morphology (specially size and shape) [27, 28]. These AgNPs exhibit localized surface plasmon resonance (LSPR) spectra (colors), enabling the monitoring of their evolution and color formation by UV–vis measurements. In this work, the aim is the development of an easy chemical method to synthesize both clusters and silver nanoparticles of different colors in aqueous polymeric solution at room temperature and in a short period of time with a well-defined shape, using PAA as protecting agent. With this goal, an experimental matrix of results is generated by changing two parameters: the concentration of the protecting agent PAA (from 1 to 250 mM); and the different molar ratio between the reducing agent, dimethylaminoborane (DMAB) (concentration from 0.033 to 6.66 mM), and the loading agent, silver nitrate (AgNO3) (at a fixed concentration of 3.33 mM).