Nanocomposites of silver nanoparticle and dinonylnaphthalene disulfonic acid‐doped thermoreversible polyaniline gel

Abstract

Silver/polyaniline‐dinonylnaphthalene disulfonic acid (PANI‐DNNDSA) gel nanocomposites are prepared from the reduction of silver salt by polyaniline in formic acid medium. Scanning electron micrographs (SEM) indicate the presence of three‐dimensional fibrillar network structure and the silver nanoparticles remain dispersed within the PANI‐DNNDSA fibrillar network. Differential scanning calorimetric (DSC) study shows reversible first‐order phase transition characterizing the composite to behave as a thermoreversible gel. Transmission electron micrographs (TEM) show a decrease of nanoparticle size with increasing AgNO3 concentration. Wide angle X‐ray scattering (WAXS) patterns show lamellar structure in the gel as well as in the gel metal nanocomposites (GMNCs) and the two melting peaks in the DSC patterns correspond to the melting of monolayer and bilayer crystals produced from the interdigitation of DNNDSA tails anchored from PANI chains within the PANI lamella. The above melting points are greater in the GMNCs than that of pure gel indicating the formation of complex melting thermogram with crystallites produced from the anchored surfactants tails at the surface of Ag nanoparticles. The GMNCs show a higher thermal stability than that of pure PANI‐DNNDSA gel. PANI‐DNNDSA gel has an emission peak at 354 nm but fluorescence quenching occurs in the GMNCs and the emission peak becomes red shifted. Also in the UV–vis spectra the π band‐polaron band transition peak shows a red shift and the DC conductivity increases with increasing Ag nanoparticle concentration in the GMNCs. The current (I)–voltage (V) characteristic curves indicate Ohmic nature of conductivity of the gel and the current at the same voltage increases appreciably with increasing Ag nanoparticle concentration. These GMNCs are easily processible due to its thermoreversible nature. So, an easily processible, thermally stable and highly conducting DNNDSA‐doped PANI‐Ag gel nanocomposite with interesting photoluminescent property has been successfully developed suitable for optoelectronic applications. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers

Enhancement of Energy Storage and Photoresponse Properties of Folic Acid–Polyaniline Hybrid Hydrogel by in Situ Growth of Ag Nanoparticles

“…Thus, from the UV–vis study, it is proven that the PANI molecules are present in the doped state (i.e, in the PANI (ES) form). This is similar to the nanocomposite of AgNP and polyaniline doped with dinonylnapthalene disulfonic acid, where polaronic bands are observed . Similar in situ growth of AgNPs is also reported from an one-step synthesis in nitric acid medium using APS as initiator for AgNPs embedded over PANI nanofibers .…”

“…This is similar to the nanocomposite of AgNP and polyaniline doped with dinonylnapthalene disulfonic acid, where polaronic bands are observed. 50 Similar in situ growth of AgNPs is also reported from an one-step synthesis in nitric acid medium using APS as initiator for AgNPs embedded over PANI nanofibers. 51 It may therefore be argued that the Ag nanoparticles are produced during the oxidation of ANI to PANI, in which Ag + become reduced to AgNP, producing FP2Ag gel.…”

“…In FP2Ag gels, these peaks are not prominent; rather, a new peak is observed at 421 nm, which may be attributed to the plasmon band of AgNPs . The characteristic peaks of the AgNPs (421 nm) overlap with the polaron to -π*­(428 nm) band transition peak of PANI, resulting in a broad peak.…”

“…In FP2Ag gels, these peaks are not prominent; rather, a new peak is observed at 421 nm, which may be attributed to the plasmon band of AgNPs. 50 The characteristic peaks of the AgNPs (421 nm) overlap with the polaron to -π*(428 nm) band transition peak of PANI, resulting in a broad peak. It is interesting to note that in all of the cases, there is a peak at ∼810 nm in all of the gels and hybrid gels originating from the πband to the polaron-band transition of PANI.…”

Polymer assisted synthesis of functional nano-materials

“…Yu et al also conducted absorption spectroscopy and NMR investigation on ZnSe; and they proposed the formation of Zn-P complexes which possess higher reactivity leading to faster nucleation/growth (termed as 'indirect route') [240]. A similar concept which is 'coordination polymer' had been proposed by Owen et al; they discussed the importance of Lewis acidity of cadmium octadecylphosphonate during the monomer formation [241].6.1.3 Conducting polymer assisted synthesis of inorganic nano-crystalsMetallic nano-crystals have been synthesized inside non-conducting polymer (e.g., Au in PMMA) or conducting polymer (e.g., Ag[242], Pd[243], Au[243,244], Cu or Cu 2 O [245] in PANI). Of higher interest is the idea of synthesizing functional inorganic nano-crystals inside conducting polymers; creating hybrid nano-composites in one-step.…”