Showing papers by "Edamana Prasad published in 2016"
TL;DR: In this article, three modified binders (elastomer, plastomer and crumb rubber) and the base bitumen were subjected to different ageing conditions and the evolution of the chemical functionalities during ageing were tracked using FTIR spectroscopy.
Abstract: Modified binders exhibit complex rheological behaviour due to the interaction of the modifiers with the base binder and the manner in which they age during field applications. Quantification of the interaction and the ageing of such modified binders is currently a necessity. In this investigation, three modified binders (elastomer, plastomer, and crumb rubber) and the base bitumen were subjected to different ageing conditions and the evolution of the chemical functionalities during ageing were tracked using FTIR spectroscopy. Analysis of the spectra of modified binders immediately after the production process showed that while the elastomer modified binders exhibited physical interaction, the plastomer and crumb rubber modified binders exhibited physical and chemical interactions. During ageing, there was no subsequent evolution of the interactions and one could only see chemical functionalities related to oxidation. Analysis of the spectra showed that the carbonyl and sulphoxide exhibit identical trends ...
142 citations
TL;DR: Partial RET in the system has been utilized to generate white-light emission from the gel by incorporating an additional lanthanide ion, Tb(III), along with the organic donors and Eu(III).
Abstract: In this paper, we have investigated the use of poly(aryl ether) dendron-based gel as a medium for resonance energy transfer (RET) from organic donors (phenanthrene, naphthalene, and pyrene) to lanthanide [Eu(III) and Tb(III)] ions. The gel has been prepared through self-assembly of glucose-cored poly(aryl ether) dendrons in a dimethyl sulfoxide/water mixture (1:9 v/v). The efficiency of RET was calculated by metal-centered emission quantum yield measurements in the gel medium. While there was no resonance energy transfer observed between the donor–acceptor pairs in solution, efficient RET has been observed in the gel medium. The metal-centered quantum yield values were 11.9% for phenanthrene–Eu(III), 3.9% for naphthalene–Eu(III), and 3.6% for pyrene–Eu(III) systems. Partial RET in the system has been utilized to generate white-light emission from the gel by incorporating an additional lanthanide ion, Tb(III), along with the organic donors and Eu(III). The CIE (Commission Internationale d’Eclairage) coordi...
54 citations
TL;DR: The pure white light formation has been demonstrated at desired temperatures in both aqueous medium as well as in an agar-agar hydrogel and the SISSA prevents a fast intersystem crossing of the AnC monomer and generates an emissive state from the self-assembled AnC.
35 citations
TL;DR: In this article, a turn-on fluorescent probe based on denatured bovine serum albumin (BSA)-Pyronin Y complex (PYdBSA) was used to detect common contaminant ions (Hg2+, Cd2+, Cu2+, and Pb2+) found in wastewater.
Abstract: A “turn on” fluorescent probe based on denatured bovine serum albumin (BSA)–Pyronin Y complex (PYdBSA) has been prepared using a one pot approach. This probe can detect nanomolar concentrations of common contaminant ions (Hg2+, Cd2+, Cu2+, and Pb2+) found in wastewater. The probe shows the highest fluorescence response for Hg2+ (relative intensity set to 100%) and a very good response for Cd2+ (60%), Cu2+ (50%), and Pb2+ (20%). The probe is water-soluble and has photo excitation in the visible region (530 nm). More interestingly, the presence of the contaminant ions under consideration can be visually detected due to the distinct color formation upon addition of the analytes in micromolar (1 μM) concentrations. The limit of detection (LOD) with fluorometry is 9 nM for Hg2+ (<2 ppb; consistent with standards given by the U.S. Environmental Protection Agency). This probe signal is found to be intact even in the presence of other metal ions such as Zn2+, Co2+, Fe2+, Ag+, K+, Na+, Al3+, Ca2+, Fe3+, Ni2+, Sb3+...
22 citations
TL;DR: Density functional calculations provide deeper insights accounting for the role of charge transfer interactions in the mode of self-assembly, providing high thermo-mechanical stability to the gels compared to the native ones.
Abstract: Alteration of native gelation properties of anthracene and pyrene cored first generation poly(aryl ether) dendrons, G1-An and G1-Py, by introducing a common acceptor, 2,4,7-trinitro-9H-fluoren-9-one (TNF), results in forming charge transfer gels in long chain alcoholic solvents. This strategy leads to significant perturbation of optical and electronic properties within the gel matrix. Consequently, a noticeable increase of their electrical conductivities is observed, making these poly(aryl ether) dendron based gels potential candidates for organic electronics. While the dc-conductivity (σ) value for the native gel from G1-An is 2.8 × 10–4 S m–1, the value increased 3 times (σ = 8.7 × 10–4 S m–1) for its corresponding charge transfer gel. Further, the dc-conductivity for the native gel self-assembled from G1-Py dramatically enhanced by approximately an order of magnitude from 4.9 × 10–4 to 1.3 × 10–3 S m–1, under the influence of an acceptor. Apart from H-bonding and π···π interactions, charge transfer res...
21 citations
TL;DR: In this paper, an eco-friendly approach for the synthesis of ZnO nanostructures using the aqueous extract of pomegranate peel has been described.
Abstract: Synthesis of monodispersed nanostructures would be attractive if the synthesis is simple, one step and cost effective. In this work, an eco-friendly approach for the synthesis of ZnO nanostructures using the aqueous extract of pomegranate peel has been described. ZnO nanoflakes were formed initially upon 15 min sunlight irradiation of an aqueous solution of Zn acetate in the presence of pomegranate peel extract. We observed that the nanoflakes formed are converted to ZnO nanopencils upon mild heating. The nanopencils have been characterized by diffused reflectance spectroscopy, X-ray diffraction analysis, photoluminescence spectroscopy, FT-Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. Furthermore, we examined the photocatalytic activity of the ZnO nanopencils and compared the performance with commercial ZnO and TiO2 (P25) nanoparticles towards the photocatalytic degradation of methylene blue under direct sunlight irradiation. The total carbon removal efficiency of the ZnO nanopencils for methylene blue is 95% which was achieved by 4.5 h.
20 citations
TL;DR: The visco-elastic property of the gel enables us to develop a gel based ink from the compound, which can be read under UV-light, and the hydrophobic nature of the compound has been exploited to make self-cleaning surfaces with anti-wetting properties.
18 citations
TL;DR: The achievement of remarkable tunability of self-healing property for a low molecular weight hybrid gel, based on poly(aryl ether) dendron derivative (PAD), which has been synthesized using PAD and poly(amido amine) {PAMAM} dendrimer derivative (QPD), which are intercalated in the montmorillonite clay (MMT) layers.
Abstract: Low molecular weight gels have relatively poor self-healing capacity compared to that of polymeric gels. Induction and tuning of the healing capacity of low molecular weight gels to achieve desired applications are thus challenging tasks. The present work describes the achievement of remarkable tunability of self-healing property for a low molecular weight hybrid gel, based on poly(aryl ether) dendron derivative (PAD). The hybrid gel has been synthesized using PAD and poly(amido amine) {PAMAM} dendrimer derivative (QPD), which are intercalated in the montmorillonite clay (MMT) layers. The self-healing of the hybrid gel (QPD-MMT-PAD) was demonstrated through experiments where the distorted gel regained the initial value of storage modulus (G′) within a few minutes. Further, the propensity of self-healing of the gel has been tuned as a function of QPD concentration. The mechanically stable QPD-MMT-PAD hybrid gel has been utilized for the adsorption of ppm level concentration of polycyclic aromatic hydrocarb...
13 citations
16 Oct 2016
TL;DR: In this paper, an easy-to-make procedure of Janus dendrimers containing two widely used dendrons (poly(aryl ether) and poly(amido amine) {PAMAM}) was reported to form a hydrogel with supergelation ability.
Abstract: The present work reports an easy-to-make procedure of Janus dendrimers containing two most widely used dendrons [poly(aryl ether) and poly(amido amine) {PAMAM}], and utilize them, for the first time, to form a hydrogel with supergelation ability The first generation (G1G1) Janus dendrimer forms hydrogel with a critical gelation concentration (CGC) of 65 mg/mL, whereas the CGC for G1G15 dendrimer went as low as 090 mg/mL in DMSO-H2O mixture Judicious choice of solvent medium (ethanol-water) led to the formation of flexible morphology (long fibres to vesicles) by the Janus dendrimers, suggesting the possibility of tuning the mechanism of self-assembly in the system The dye (rhodamine B) loading efficiency in the gel was successfully carried out using different generations {G1G1 and G1G15} of the Janus dendrimer Generation G1G1 hydrogel (1 wt%) showed maximum dye loading efficiency of 4 mg/mL Rhodamine B release profiles from the Janus dendrimers were determined and the results indicate that slow release kinetics was observed in the case of G1G1, where the self-assembly is robust
9 citations
TL;DR: The use of 18-crown-6 (18-C-6) as a host system to disaggregate suitably substituted PDI derivatives in methanol led to disaggregation and enhanced emission from the systems.
Abstract: Perylene diimide (PDI) derivatives exhibit a high propensity for aggregation, which causes the aggregation-induced quenching of emission from the system. Host-guest chemistry is one of the best-known methods for preventing aggregation through the encapsulation of guest molecules. Herein we report the use of 18-crown-6 (18-C-6) as a host system to disaggregate suitably substituted PDI derivatives in methanol. 18-C-6 formed complexes with amino-substituted PDIs in methanol, which led to disaggregation and enhanced emission from the systems. Furthermore, the embedding of the PDI⋅18-C-6 complexes in poly(vinyl alcohol) (PVA) films generated remarkably high emission quantum yields (60-70 %) from the PDI derivatives. More importantly, the host-guest systems were tested for their ability to conduct electricity in PVA films. The electrical conductivities of the self-assembled systems in PVA were measured by electrochemical impedance spectroscopy (EIS) and the highest conductivity observed was 2.42×10(-5) S cm(-1) .
6 citations