PbS Nanoparticles in Polyacrylamide Matrix: Structure, Optical Properties and Influence on the Host Polymer

A synthetic procedure for the incorporation of PbS nanoparticles in a polyacrylamide (PAM) matrix was introduced. The method is based on the simultaneous polymerization of the monomer and thermal decomposition of the dithiooxamide-lead complex. XRD analysis revealed that PbS nanoparticles have a sphalerite crystal structure (galena). The TEM micrograph showed spherical particles, with average diameter of about 3 nm, well dispersed in the polymer matrix. Although a sharp edge was not observed, the optical absorption of the PAM-PbS nanocomposite is shifted towards lower wavelengths compared to the bulk PbS.SFKM 2004 : September 20–23, 2004, Sokobanja

Study of sago starch-CdS nanocomposite films: Fabrication, structure, optical and thermal properties

A synthetic procedure for the preparation of nanocomposite films of sago starch and CdS nanoparticles was introduced. The films were characterized using optical, structural, and thermal techniques. The formation of nanostructured CdS in the starch matrix was confirmed by a blue shift in the onset of absorption in the UV-VIS spectra of the nanocomposites. The average size of the nanoparticles varied from 3.6 to 5 nm, depending on the initial concentration of cadmium acetate during the nanocomposite preparation. Fluorescence measurements of the sago-CdS nanocomposite film showed broad emission in the orange-red part of the spectrum. DSC; and TGA analyses revealed significant effects of CdS nanoparticles on the thermal properties of the starch matrix

Composites comprising CdS nanoparticles and poly(ethylene oxide): optical properties and influence of the nanofiller content on the thermal behaviour of the host matrix

Tri-n-octylphosphine oxide-capped CdS nanoparticles were synthesized with the cadmium(II) complex of thiocarbohydrazide as a precursor. Nanocomposites were prepared by mixing a toluene solution of poly(ethylene oxide) (PEO) and the obtained CdS nanoparticles. The ultraviolet-visible spectroscopy measurements showed a blue shift of the onset of optical absorption, compared to bulk CdS, which confirmed the presence of nanostructured CdS. A transmission electron microscopy micrograph of the nanocomposite depicted that the nanoparticles are well dispersed in the PEO matrix. Differential scanning calorimetry analysis revealed hindered crystallization of PEO in the presence of CdS nanoparticles. It was also found that increasing the nanoparticle content led to the shift of the onset of decomposition of the matrix towards higher temperature

Biopolymer-protected CdSe nanoparticles

A synthetic procedure for the encapsulation of cadmium selenide (CdSe) nanoparticles in a sago starch matrix is introduced. The nanocomposite was investigated using structural, spectroscopic and thermal, methods. TEM micrographs of the nanocomposite showed spherical CdSe particles of 4-5 nm in size coated with a biopolymer layer. The absorption edges of both the aqueous solution and the thin film of the CdSe-starch nanocomposite were shifted toward lower wavelengths in comparison to the value of the bulk semiconductor. Infrared measurements revealed that the interaction of CdSe nanoparticles and starch chains takes place via OH groups. Although the onset of the temperature of decomposition of CdSe-starch nanocomposite is lower than that of the pure matrix, thermogravimetric analysis also showed that introduction of CdSe nanoparticles significantly reduced starch degradation rate leading to high residual mass at the end of the degradation process. (C) 2009 Elsevier Ltd. All rights reserved

Inhibition of Microbial Growth by Silver-Starch Nanocomposite Thin Films

A sago starch biopolymer with embedded silver nanoparticles has been studied as a material for the prevention of microbial growth. Approximately 8 nm in size, silver nanoparticles have been synthesized by reduction of the silver salt in aqueous solution in the presence of sago starch using sodium borohydride as a reducing agent. The obtained solutions were cast on glass plates to obtain thin supported silver-starch nanocomposite films. The morphology of the nanocomposites was investigated by scanning and transmission electron microscopy. UV-Vis absorption spectroscopy showed that during the film formation a part of the silver nanoparticles has been trapped in the water present in the sample, which enabled their partial oxidation into active Ag(+) species. The oxidation of the silver nanoparticles was confirmed by X-ray photoelectron spectroscopy. The antimicrobial activity tests have shown that the nanocomposite material can be successfully employed to prevent the viability and growth of the common pathogens Staphylococcus aureus, Escherichia coli and Candida albicans. (C) Koninklijke Brill NV, Leiden, 201

Adsorption of sulfur onto a surface of silver nanoparticles stabilized with sago starch biopolymer

Adsorption of sulfide ions onto a surface of starch capped silver nanoparticles upon addition of thioacetamide was investigated. UV-vis absorption spectroscopy revealed that the adsorption of the sulfide ion on the surface of the silver nanoparticles induced damping as well as blue shift of the silver surface plasmon resonance band. Further increase in thioacetamide concentration led to shift of the resonance band toward higher wavelengths indicating the formation of the continuous Ag2S layer on the silver surface. Thus fabricated nanoparticles were investigated using electron microscopy techniques (TEM, HRTEM, and HAADF-STEM) and X-ray photoelectron spectroscopy (XPS), which confirmed their core-shell structure. (C) 2009 Elsevier B.V. All rights reserved