Nano-sized CdS particles with a diameter of about 6 nm and a relatively narrow size distribution were synthesized in inverse micellar solution. In-situ chemical modification of the surface of these particles was carried out by imidazole and thiol molecules, respectively. The morphologies of the particles dispersed in varous solvents were analyzed by TEM observation. FTIR and XPS measurements proved the chemical bonding between the particles and the surface modifiers. UV-Vis absorption and fluorescence emission spectra of CdS suspension in solvents revealed that the surface modification had blocking effects on the surface defects that caused radiationless recombination of charge carriers. The solubility of these re-dispersible nano-powders in different solvents was studied as a function of surface modifier species, modifier dosage as well as solvent effects. The preliminary conclusion is that thiol is more appropriate than imidazole to produce uniform polymer nanocomposites.

Synthesis of nanometer-sized clusters of CdS in inverse-micellar solution and in situ chemical derivatization of the surface of these cluster compounds were studied in the current paper. The nanoparticle surface can be terminated and passivated by the addition of imidazole and thiol molecules, which allows of inhibiting the particle from agglomeration, improving particle distribution in organic solvents and polymer matrices, and blocking surface defects that cause radiationless recombination of charge carriers. The solubility of these re-dispersible powders in different solvents was studied, and then the CdS quantum dots–polymer composites were prepared using solution mixing method. By means of optical, structural and thermal characterization techniques, the particle distribution and interfacial interaction in the composite systems and their influence on the properties of quantum CdS were revealed in detail.

A nano-sized CdS particles was incorporated into polymer films by solvent mixing, casting and evaporating methods.The CdS particles of about 6 nm in size were prepared through micro-emulsion and in-situ surface modification with thiol and imidazole,respectively.It is proved that imidazole modification promotes the dispersion of these nanoparticles into PMMA,while thiol modified ones can be uniformly dispersed into PS matrix due to the selective solubility among the surface modifiers,solvents and polymers.The resultant polymer composites were characterized using optical, structural and thermal techniques.FTIR measurements revealed the formation of strong bonding between the particles and the polymer matrices Besides the surface modifier,the polymers also help to block the surface defects that trap the charge carriers,resulting in enhanced light absorption and emission benavior On the other hand,in the presence of CdS particles,the thermal decomposition temperatures of PMMA and PS shifted towards higher temperature region,further demonstrating the interaction between the particles and the polymers. The mechanisms accounting for the variation in the composites optical properties with CdS content and the amount of the surface modifiers were explained on the basis of the effects of surface modifier morphologies, dispersion status of the particles, and the complex interaction among the particles, surface modifiers and polymers.

Highly filled polystyrene (PS) composite film with a nano-CdS loading of 20wt.% can be obtained when a certain mercaptan is applied to the particles' surfaces. Because of a strong electron transfer interaction between the modified CdS nanoparticles and the aliphatic carbons in PS, self-organization of the nanoparticles is perceivable in the composites. As a result, the ultraviolet/visible absorption edge of the treated nano-CdS/ PS composites is blue-shifted in addition to the shift caused by quantum size effect. The fluorescence emission peak is accompanied by some fine structures and becomes redshifted and narrower. Unlike conventional nanocomposites that generally contain low concentrations of nanoparticles (less than 10wt.%), the present approach greatly improves the scope for cooperative behavior of the nanoparticles.

Ｓｉｌｖｅｒｎａｎｏｐａｒｔｉｃｌｅｓｗｉｔｈｄｉｆｆｅｒｅｎｔｄｉａｍｅｔｅｒｓｗｅｒｅｓｙｎｔｈｅｓｉｚｅｄｂｙｍｉｃｒｏｅｍｕｌｓｉｏｎｍｅｔｈｏｄ ,ｉｎｗｈｉｃｈｔｈｅｅｆｆｅｃｔｏｆｔｏｌｕｅｎｅｏｒｃｙｃｌｏｈｅｘａｎｅａｓａｎｏｉｌｐｈａｓｅｏｎｔｈｅｐａｒｔｉｃｌｅｓｉｚｅａｎｄｉｔｓｄｉｓｔｒｉｂｕｔｉｏｎｗａｓｄｅｔｅｃｔｅｄ .Ｓｉｌｖｅｒｎａｎｏｐａｒｔｉｃｌｅｓｗｅｒｅｎｅａｒ ｓｐｈｅｒｉｃａｌ,ｂｏｔｈｍｕｌｔｉｃｒｙｓｔａｌｓａｎｄｔｗｉｎｓｗｅｒｅｏｂｓｅｒｖｅｄ.Ｌａｔｔｉｃｅｄｅｆｏｒｍａｔｉｏｎｓｅｘｉｓｔｅｄｉｎｄｉｆｆｅｒｅｎｔｄｅｇｒｅｅｓｂｅｃａｕｓｅｔｈｅｉｎｔｅｒｐｌａｎａｒｓｐａｃｅｄｗａｓｉｎｃｒｅａｓｅｄ.Ｔｈｅｆｌｕｏｒｅｓｃｅｎｃｅｓｐｅｃｔｒａｆｏｒｄｉｆｆｅｒｅｎｔｓｉｚｅｓｉｌｖｅｒｎａｎｏｐａｒｔｉｃｌｅｓｄｉｓｐｅｒｓｅｄｉｎｏｒｇａｎｉｃｓｏｌｖｅｎｔｓｗｅｒｅｍｅａｓｕｒｅｄ.Ｔｈｅｒｅａｒｅｔｈｒｅｅｅｍｉｓｓｉｏｎｐｅａｋｓｆｏｒｓｉｌｖｅｒｎａｎｏｐａｒｔｉｃｌｅｓ ｃｈｌｏｒｏｆｏｒｍｓｙｓｔｅｍｓ,ｗｈｉｌｅｎｏｆｌｕｏｒｅｓｃｅｎｃｅｅｍｉｓｓｉｏｎｗａｓｆｏｕｎｄｗｈｅｎｓｉｌｖｅｒｎａｎｏｐａｒｔｉｃｌｅｓｄｉｓｐｅｒｓｅｄｉｎｔｏｌｕｅｎｅ .Ｔｈｅｆｌｕｏｒｅｓｃｅｎｃｅｉｎｔｅｎｓｉｔｙｖａｒｉｅｓｗｉｔｈｐａｒｔｉｃｌｅｓｉｚｅｏｆｔｈｅｓｉｌｖｅｒｎａｎｏｐａｒｔｉｃｌｅｓ,ｗｈｉｃｈｏｒｉｇｉｎａｔｅｓｆｒｏｍＡｇ2 ,Ａｇ3 ｃｌｕｓｔｅｒｓｏｎｔｈｅｓｉｌｖｅｒｐａｒｔｉｃｌｅｓｕｒｆａｃｅｐｒｏｄｕｃｅｄｂｙｔｈｅｉｎｔｅｒａｃｔｉｏｎｂｅｔｗｅｅｎｓｉｌｖｅｒａｎｄｃｈｌｏｒｏｆｏｒｍｕｎｄｅｒＵＶｒａｄｉａｔｉｏｎ .Ｔｈｅｒｅａｃｔｉｖｉｔｙａｎｄｔｈｅｎｕｍｂｅｒｏｆｓｕｒｆａｃｅｒｅａｃｔｉｖｅｃｅｎｔｅｒｓｖａｒｙｗｉｔｈｓｉｌｖｅｒｐａｒｔｉｃｌｅｓｉｚｅ,ｒｅｓｕｌｔｉｎｇｉｎｔｈｅｄｉｆｆｅｒｅｎｔｆｌｕｏｒｅｓｃｅｎｃｅｐｈｅｎｏｍｅｎａ.

Preparation of nano-CdS particles with surface thiol modification by microemulsion method and their influences on the particle size distribution in highly filled polystyrene-based composites were studied. The modified nano-CdS was characterized by X-ray photoelectron spectroscopy (XPS), light absorption and emission measurements to reveal the morphologies of the surface modifier, which are consistent with the surface molecules packing calculation. The morphologies of the surface modifier exerted a great influence not only on the optical performance of the particles themselves, but also on the size distribution of the particle in polystyrene matrix. A monolayer coverage with tightly packed thiol molecules was believed to be most effective in promoting a uniform particle size distribution and eliminating the surface defects that cause radiationless recombination. Control of the particles size distribution in polystyrene can be attained by adjusting surface coverage status of the thiol molecules based on the strong interaction between the surface modifier and the matrix.

Self-organization of nano-CdS particles in polystyrene can be observed by encapsulating the particles with ndodecyl mercaptan owing to a strong electron transfer interaction between the modified CdS nanoparticles and aliphatic carbons in polystyrene.Consequently,ultraviolet/visible absorption edge of the treated nano CdS/polystyrene composites is further blueshifted in addition to the shift caused by the quantum size effect,and the fluorescence emission peak of the composite becomes redshifted and narrow.

Polymer films (polystyrene and acrylonitrile–styrene copolymer) filled with silver nanoparticles were analyzed by optical absorption spectrometry, X-ray photoelectron spectrometry and laser ablation/time-of-flight mass spectrometry. The results indicated that optical absorption of polymer films was affected by Ag nanoparticles and the interfacial interactions between Ag and the polymer matrices, and the latter was highly dependent on the chemical structure of the polymers. The mass spectral data further demonstrated that the incorporation of Ag nanoparticles into polymers significantly changed the laser ablation mechanism and the products of the polymers. As a result, nano-Ag/polymer films showed a Ag-induced laser-decomposition behavior accompanied by a series of carbon cluster negative ions.

Surface-modified silver nanoparticles with various sizes, synthesized by water-in-oil micro-emulsion, were incorporated into polystyrene (PS) to form transparent nanocomposite films through solution-mixing and static-casting. It was found that the Ag nanoparticles could be re-dispersed well in the polymer matrix by using chloroform as a solvent due to a strong interaction between Ag and chloroform. XPS analysis suggested that there is no obvious interaction between nanosilver and the polystyrene matrix. The third-order nonlinear optical susceptibility of Ag/PS nanocomposite films is around (10).esu and increases with increasing particle size, as measured by the time-resolved femtosecond optical Kerr effect experiment at a wavelength of 830nm. The results demonstrate that the present fabrication approach can effectively tailor the structure and properties of the nanocomposites.

The Effect of silver nanoparticles on laser ablation of PS and PMMA were studied by time of flight mass spectrometer. After adding silver nanoparticles, the way of laser ablation for polymer was changed. Silver nanoparticles can lead to carbonization of PS and PMMA, even graphitization of polymer in the surface of silver. The effect of silver nanoparticle was related to the interaction and Structure of interface between silver and polymer, so for nano-Ag/PMMA system, the reaction in the interlayer of composite induced by thermal treatment, which was proved by DSC, can reduce the carbonization of PMMA.

Surface--modified silvers nanoparticles with different size were prepared by microemulsion, the interface interaction, dispersity and optical properties of silver nanoparticles/organic solvent systems were investigated by ESR, TEM and UV/VIS spectroscopy. Results showed that there is a series of surface local paramagnetic sites in surface-modified silver nanoparticles, which made the relation between ESR's parameters and particle size deviate from Kawabata's, description. There is a Strong interaction between silver nanoparticles and chloroform, the smaller the particle was, the stronger the interaction was. The dispersity of nanoparticles was influenced by particle size and the time of ultrasonic process. It has been found that chloroform, as an excellent solvent for silver nanoparticles and many polymers. could be used to prepare polymeric nanocomposites by means of solution mixing, so it's easy to adjust the aggregated structure of nanoparticles and their optical properties.