Tne New Methods Of Preparation Of Nanoparticles/Polymer Composite Materials

Due to the unique physical and chemical properties of inorganic nanoparticles (NPs), such as unique size-dependent optical, electrical, and mechanical properties, they are potentially applicable in many fields. In particular, NPs are significant and promising candidates in the applications of biology, diagnosis and electronics, for example, indicator to detect metal ions, as labels for DNA and protein detection, as tracers for the localization of marked proteins, as electron acceptor for LED, as building block for photo crystals, and so forth. However, the poor stability as the inherent defect of the NPs limits the progress for their applications. Therefore, many efforts have been devoted to coat NPs with polymers, namely, fabricating NP-polymer composites. On the one hand, as an inert media, the coating of polymers will enhance the stability of NPs toward bad environments. On the other hand, polymers may endow NPs with new functionalities, such as water solubility, chemical conjugation, stimuli-response, and so forth. In this paper, some methods have been used to form different kind of NPs-polymer composites, and we hope to get a new NPs-polymer composite material with special response function.Firstly, by combining the phase transfer of Au3+ from water to chloroform using quaternary ammonium surfactant and NaBH4 reduction, we used polymerizable surfactant OVDAC to direct synthesize Au NPs. The average diameter of the Au NPs was about 11nm, and they can be dissolved in organic solvent very well. The experimental results revealed that the morphology and the size distribution of NPs were mainly determined by the amount of OVDAC and NaBH4. Moreover, OVDAC-stabilized NPs were directly used as macromolecular monomers in the copolymerization with lipophilic monomers. Because of the styrene segment of OVDAC, a covalent linkage was obtained between NPs and polymer media, which prevented the aggregation of NPs and therewith improved the transparency of the resulting bulk nanocomposites. This method was also available for synthesizing other metal NPs, for example Ag, Pd, and Pt, and semiconductor NPs, for example ZnS, CdS, and PbS, thus providing a series of NP-containing macromolecular monomers for further design and synthesis of functional nanocomposites.Secondly, we demonstrated a general method for fabricating water-dispersible NP-polymer composite microspheres from different NPs with specific functionalities. The amphiphilic polymer poly(maleic anhydride-alt-octadecene) (PMAO) were modified by poly(ethylene glycol) (PEG) in order to enhanced the lipophilic property of the PMAO. The water-dispersible NP-polymer composite microspheres were fabricated through the self-assembly of amphiphilic poly(ethylene glycol) diglycidyl-grafted poly(maleic anhydride-alt-octadecene) (PMAO-g-PEG) and NPs, which is general for various lipophilic NPs and the hydrophilic NPs after lipophilic modification. Depending on the species of NPs, the diameters of the resultant microspheres are in the range of 80 to 500 nm. The embedment of NPs into microspheres greatly enhanced the PL stability in acidic range, permitting the detection of metal ions at low pH conditions. Although the improved tolerance toward various ions decreased the sensitivity in detection with 2 magnitudes, it in return broadened the concentration range of detection with 7 magnitudes. Current method for fabricating composite microspheres was facile and feasible, which will promote the technical applications of functional NPs in detection and diagnosis.Thirdly, the micelles of polystyrene-block-poly(2-vinyl pyridine) (PS-b-P2VP) were formed by altering the polarity of the solution. The size distribution of micelles was narrow, and the diameter of the polymer micelles was about 55nm. After the aqueous CdTe nanoparticles was modified by DDAB, the lipophilic NPs would move to the inside of the polymer micelles in the aqueous solution though the self-assembly because of the hydrophobic-hydrophobic interaction. The CdTe NPs-polymer composite micelles keep the luminescent property of the original CdTe NPs, and the the PL stability in acidic range would be enhanced greatly. Then, two fluorescent color CdTe NPs were composed into one micelle, the florescent of the composite micelles would be changed by altering the pH of the solution because of the forster resonance energy transfer between these two kinds of NPs.