K. Jayamoorthy

Development of silane grafted ZnO core shell nanoparticles loaded diglycidyl epoxy nanocomposites film for antimicrobial applications

In this article a series of epoxy nanocomposites film were developed using amine functionalized (ZnO-APTES) core shell nanoparticles as the dispersed phase and a commercially available epoxy resin as the matrix phase. The functional group of the samples was characterized using FT-IR spectra. The most prominent peaks of epoxy resin were found in bare epoxy and in all the functionalized ZnO dispersed epoxy nanocomposites (ZnO-APTES-DGEBA). The XRD analysis of all the samples exhibits considerable shift in 2θ, intensity and d-spacing values but the best and optimum concentration is found to be 3% ZnO-APTES core shell nanoparticles loaded epoxy nanocomposites supported by FT-IR results. From TGA measurements, 100wt% residue is obtained in bare ZnO nanoparticles whereas in ZnO core shell nanoparticles grafted DGEBA residue percentages are 37, 41, 45, 46 and 52% for 0, 1, 3, 5 and 7% ZnO-APTES-DGEBA respectively, which is confirmed with ICP-OES analysis. From antimicrobial activity test, it was notable that antimicrobial activity of 7% ZnO-APTES core shell nanoparticles loaded epoxy nanocomposite film has best inhibition zone effect against all pathogens under study.

Twin Applications of Tetra-Functional Epoxy Monomers for Anticorrosion and Antifouling Studies

This paper reports the development and characterization of nano-hybrid coatings using tetraglycidyl 2,2-bis(4-(4-amine phenoxy)phenyl)propane (TGBAPPP) and 3-aminopropyltriethoxysilane (APTES) functionalized ZnO as nano-reinforcement. The nano-hybrid coatings were cured by aromatic and aliphatic curing agents. The effect of the ZnO-APTES and curing agents on the corrosion and fouling resistant properties of these coatings was studied by electrochemical impedance, antifouling tests and toxicity test. It shows the tetraglycidyl epoxy nano-hybrid coatings have a better set of coating properties when compared to di-functional epoxy nano-hybrid coatings. The best results were obtained for ZnO-APTES loaded TGBAPPP with curing agent Aradur 140. These observations clearly indicate the synergistic effect of curing agent and nano-reinforcing effect of ZnO-APTES towards corrosion resistance.

Experimental and Theoretical Investigations of Tetrakis (Thiourea) Palladium Chloride Semi-Organic Non-Linear Optical Crystal: An Approach to NLO Application

Semi-organic non-linear optical crystals of tetrakis (thiourea) palladium chloride (TTPC) were synthesized by a slow evaporation method. X-ray diffraction analysis performed on the title crystal established its orthorhombic structure and Pna2 1 space group. The crystalline perfection was investigated by means of high resolution X-ray diffraction (HRXRD) measurements. The values of transmittance, cutoff wavelength, refractive index and single oscillator parameters were computed through ultraviolet (UV) transmittance analysis. The second harmonic generation efficiency (SHG) of the TTPC crystals was verified by the Kurtz Perry technique. The potential of TTPC to act as a NLO material was further envisaged by the hyperpolarizability studies which resulted in higher values of dipoles and polarizability. To shed light on the pattern of charge distribution and donor-acceptor interactions prevailing in TTPC crystals, natural bond orbital (NBO) analysis was performed. Laser damage threshold (LDT) analysis on TTPC resulted in a LDT value of 5.1 GW/cm 2. The low birefringence value calculated from birefringence patterns attested the to suitability of the crystal to be used in harmonic generation devices. Using the HOMO-LUMO approach the values of significant global chemical molecular reactivity descriptors were determined.

Synthesis, NMR Spectral and DFT Studies of Styryl Imidazole Derivatives—Nano-SiO2 as an Efficient Catalyst

A series of novel styryl imidazole derivatives has been designed and synthesized using nano-SiO2 as an efficient catalyst. Synthesized compounds have been characterized by 1H and 13C-NMR spectral studies. The significant features of this nanocatalyst are high product yield, short reaction times and a vast range of substrates usage. Proton and 13C chemical shifts of the synthesized compounds were calculated. Single crystal XRD analysis has been carried out to confirm the structure of MDPI (1-(3-methoxyphenyl)-4, 5-dimethyl-2-phenyl-1H-imidazole) and it shows the imidazole ring is essentially planar and triclinic crystal. Optimization of compound MDPI was performed by DFT at B3LYP/6-31G (d, p) using Gaussian-03. Imidazole derivatives were used to construct highly sensitive fluorescent chemosensors for sensing of metal ions.

Distribution of Heavy Metals in the Marine Sediments of Various Sites in Karaichalli Island, Tuticorin, Gulf of Mannar, India

The study of heavy metals in the sediments of coral islands is significant in understanding the distribution levels and the cause of anthropogenic impacts along the marine environment. A large number of heavy metals is discharged through domestic and industrial effluents along the coastal area of the southeast coast of India. In this work the sediments from Karaichalli island of Tuticorin were collected and the samples subjected to a total digestion technique and major and trace elements concentration estimated. To interpret and assess the contamination status for heavy metals in sediments, four metal pollution indices were assessed using a enrichment factor, a geo-accumulation index, contamination factor and pollution load index. The results were treated with SPSS 16.0 software for statistical analysis like Correlation matrix and Principal component analysis. The average metal accumulation levels in coral samples of the study area is in the following order: Fe > Mn > Zn > Cu > Ni > Pb > Cr > Cd > As > Co.

Investigation of the Thermal and Dielectric Behavior of Epoxy Nano-Hybrids by using Silane Modified Nano-ZnO

The present work focuses on a comparative study of the thermal and electrical behavior of diglycidyl ethers of bisphenol-A (DGEBA) to uncover the suitability for its use in high performance applications. An epoxy nanohybrids coating was developed using aminosilane functionalized ZnO (1, 3, 5 and 7 wt%) as the dispersed phase and commercially available DGEBA as the matrix phase, with curing using triethylenetetramine (TETA). The structural features of these materials were ascertained by FTIR spectral studies, SEM and AFM analyses. The peak shift in all the samples at ∼ 1032 cm−1 explains the etheric linkage of ZnO-APTES core shell nanoparticles with the DGEBA virgin epoxy resin. The thermal behavior of the diglycidyl resins and their corresponding nano-hybrids was studied by TGA and DSC. The first decomposition stage of DGEBA neat epoxy resin starts at 325 °C and the second stage at 513.2 °C which varied in all epoxy nanocomposites. Further thermodynamic parameters are calculated using the Coats-Redfern method from TGA results to examine the thermal stability. The sample with 3% ZnO-APTES-DGEBA film exhibits the highest activation energy of 26.20 kj/mol. The dielectric permittivity, dielectric loss and AC conductivity variation with frequency, temperature and filler concentration were studied using an impedance analyzer. The variation in electrical behavior is more pronounced in 1 and 7% ZnO-APTES-DGEBA epoxy nanocomposites.

Experimental and Computational Studies of Bis(thiourea) Lead Chloride: Semi-organic Material for NLO Applications

Non liner optical single crystals of bis(thiourea) lead chloride (BTLC), belonging to the semi-organic material category, have been prepared by a slow solvent evaporation process. The single crystal X-ray diffraction analysis indicated the orthorhombic crystal structure and non-centrosymmetric Pna21 space group of the BTLC crystal. The crystalline nature of BTLC has been verified by means of the high resolution XRD (HRXRD) method. With the aid of elemental analysis, the purity and the stoichiometry of the crystal have been validated. Etching studies have been performed on BTLC using water etchant. The nature of electronic transitions, significant optical constant values and single oscillator parameters have been identified through ultra violet transmittance studies. The laser damage threshold (LDT) value of BTLC has been determined from LDT analysis. Theoretical calculations have been performed using the density functional theory (DFT) and the values of polarizability, hyperpolarizability and dipole moment of BTLC have been elucidated. Natural bond analysis (NBO) has also been done in order to gain knowledge on the nature of donor-acceptor interactions and charge distributions existing in the BTLC crystal. The frontier orbital HOMO-LUMO gap analysis assisted in arriving at the values of important global chemical molecular reactivity descriptors.