Abstract
Silver nanoparticles within a host polymer of chitosan were synthesized by using in situ method. Ultraviolet-visible spectroscopy was then carried out for the prepared chitosan : silver triflate (CS : AgTf) samples, showing a surface plasmonic resonance (SPR) peak at 420 nm. To prepare polymer composites with reduced energy band gap, different amounts of alumina nanoparticles were incorporated into the CS : AgTf solution. In the present work, the results showed that the reduced silver nanoparticles and their adsorption on wide band gap alumina (Al2O3) particles are an excellent approach for the preparation of polymer composites with small optical band gaps. The optical dielectric loss parameter has been used to determine the band gap experimentally. The physics behind the optical dielectric loss were interpreted from the viewpoint of quantum mechanics. From the quantum-mechanics viewpoint, optical dielectric loss was also found to be a complex equation and required lengthy numerical computation. From the TEM investigation, the adsorption of silver nanoparticles on alumina has been observed. The optical micrograph images showed white spots (silver specks) with different sizes on the surface of the films. The second semicircle in impedance Cole-Cole plots was found and attributed to the silver particles.
Highlights
Ion-conducting polymers, which are solid-state solutions of salts in polymers, are nowadays becoming an active area of material researches [1, 2]
It is obvious that a surface plasmonic resonance (SPR) peak at 428 nm is exhibited for the chitosan : silver triflate (CS) : a magnetic stirrer. Silver triflate (AgTf) system, while this peak is absent in the spectrum of pure CS sample
It can be seen from the figures that all the samples possess the SPR peak at around of 423 nm, which can be related to the existence of silver nanoparticles
Summary
Ion-conducting polymers, which are solid-state solutions of salts in polymers, are nowadays becoming an active area of material researches [1, 2]. The existence of amino and hydroxyl functional groups on CS’s backbone structure are the unique properties that separate CS from other biopolymers [10, 11] Polymers, such as CS, poly(ethylene oxide) (PEO), poly(2-ethyl-2-oxazoline) (POZ), and poly(vinyl pyrrolidone) (PVP), containing polar. Earlier works established that lone-pair electrons on the functional groups of polar polymers are responsible for the complexation and reduction of silver ions to silver nanoparticles [13,14,15,16] This phenomenon (i.e., Ag+ → AgO) limits the application of silver-based ionconducting polymer electrolytes in electrochemical devices [17, 18]. The results of the current study reveal that the adsorption of silver nanoparticles on Al2O3 structure through the host polar polymers produces polymer composites with small optical band gaps
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