The Synthesis And Properties Of The Nanoparticles/PMMA Composites

Elaboration of nanocomposite system by embedding of nanoparticles into polymeric matrix can afford a new class of polymeric materials which combine the properties of nanoparticles with the processability and flexibility of organic polymer matrix. In this thesis, CdSe/PMMA and ZnO/PMMA nanocomposites were prepared and their properties were preliminarily explored. The main results achieved in this thesis are listed as below:1. The TOPO and OA modified CdSe nanoparticles were synthesized by a hot injection method. ZnO nanoparticles were prepared by a sol-gel method. Using such synthesized nanoparticles, the nanoparticles/PMMA nanocomposites were prepared by a blending method.2. Photoluminescence (PL) spectra show that there is only one broad luminescence band of the TOPO-modified CdSe/PMMA nanocomposite, which peaks around 478nm; while there are two luminescence bands peaking around 400 and 510 nm respectively for the OA-modified CdSe/PMMA nanocomposite, which are respectively related to PMMA and CdSe nanoparticles. It is suggested that the PL of CdSe/PMMA nanocomposites is dependent on the modification of the CdSe nanoparticles.3. With the extension of laser radiation, for the OA-modified CdSe naoparicles/PMMA nanocomposite, its PL spectra are manifested as the weakening of PMMA-related peak and the strengthening and slight red-shift of nanoparticles-related peak; while for the TOPO-modified CdSe naoparicles/PMMA nanocomposite, the broad PL band also exhibits a red-shift. Such phenomena are preliminarily ascribed to the change of surface modification of nanoparticles by the laser radiation and energy-transfer between the PMMA matrix and nanoparticles.4. PL spectra show that the near-band-edge (NBE) emission is weaker than the defect-related emission for the stand-alone ZnO nanoparticles; while the NBE emission is stronger than the defect-related emission for the ZnO nanoparticles incorporated into the ZnO/PMMA nanocomposite. This means that the PMMA can well passivate the defects of the ZnO.5. Two fibres were drawn from PMMA and CdSe/PMMA nanocomposite respectively. The light transmissions at the wavelength larger than 600 nm are comparable for the two fibers. However, for the shorter wavelengths, the light transmission of the fiber derived from the composites is reduced faster than that of the fiber derived from PMMA, due to that the CdSe nanoparticles substantially absorb the light. Moreover, if using the light with appropriate short wavelength as the optical source for the fiber, the CdSe/PMMA nanocomposite fiber becomes an active one, which could find application in the optical gain devices.