Fabrication And Characterization Of PAN-PMMA Composite Nano Particles

The applications of polymer microspheres have been developed from general industry to advanced fields, including medicine, biochemistry, electronics and information, in the modern science and technologies for their unique dimension and morphology. A variety of synthetic routes have been designed to prepare polymer spheres and great progress has been made on the rescearch of the spheres size,morphology, performances and forming mechanism.The aim of this paper is to study the preparation of polymeric nanospheres as the precursor of carbon nanospheres via pre-oxidization and carbonization treatments. The study focuses on the emulsion polymerization technique for the preparation of narrowly size-distributed poly(methyl methacrylate)(PMMA) latex, polyacrylonitrile(PAN) latex, and two PMMA-PAN composite latexes.Two composite nanospheres based on PAN and PMMA were synthesized by a seed emulsion polymerization, using sodium dodecyl sulphate (SDS) and2,2’-azobisi-sobutyronitrile (AIBN) as the surfactant and initiator, respectively. Narrowly distributed PAN or PMMA nanospheres were first prepared by a modified emulsion polymerization. The composite nanospheres were then prepared via polymerization of another monomer, which was added drop-wise, in the presence of the seed latexes.The average hydrodynamic diameter and polydispersity index of various nanospheres were determined by dynamic light scattering (DLS). Fourier transform infrared spectrometry (FTIR) and Elementary analysis were used to analyze the chemical composition of the nanospheres. The morphologies of various nanospheres were observed by Transmission electron microscopy (TEM), Scanning electron microscope (SEM), and Atomic force microscope (AFM). Especially, staining with PTA, selective solvent treatment and ultra-thin slice technique were adopted to disclose the core-shell structure of the composite nanospheres. The results show that the seed PAN nanospheres were loosely-packed, while the seed PMMA nanospheres were closely-packed. The size both of the PAN nanospheres and PMMA nanospheres were fairly uniform with a small polydispersity index. The PAN/PMMA composite nanospheres with PAN cores wrapped by a thin layer of PMMA were produced via seed emulsion polymerization. However, more work needs to be done to disclose the detailed structure of the PAN/PMMA composite nanospheres.