Metal-Containing Nano-particles in Polymeric Matrices
aInstitute of General and Inorganic Chemistry, Russian Academy of Sciences,
Moscow 119991 RUSSIA
bSaratov State Technical University
This is an abstract
for a presentation given at the
Foresight Conference on Molecular Nanotechnology.
There will be a link from here to the full article when it is
available on the web.
The preparation in the kilogram-scale of uniform polymermetallic nanomaterials using conventional techniques is rather difficult. The creation and future utilization of such types of nano-size systems require the development of new technological processes.
A universal method of introduction of metall-containing nano-particles in polymeric matrices has been developed, which allows the fabrication of large amounts (kilogram-scale) of polymer nanoparticle composites. The encapsulation was done by thermal decomposition of metallcontaining compounds (MRn; M = Cr, Mo, W, Ti, Zr, Fe, Co, Ni, Pd, Pt, Cu; R = CO, HCOO, CH3COO, C6H5CH2) in solution-melt of polymer (polyethylene, polypropylene, polytetrafluoroethylene, polyamide, polyarylate, polycarbonate, polysterene, polyethers, polyphenyleneoxide, siloxane). For the preparation of heterometallic nanoparticles we used as a rule available heterometallic MCC; in some case labile heterometallic MCC were prepared in solution immediately before adding in reaction mixture. The optimum conditions are developed for the decomposition of MCC in order to introduce complicated and highly reactive nanoparticles into the polymeric matrix. For the subsequent characterization we have used TEM, small-angle X-ray scattering (SAXS), X-ray RED, EXAFS, X-ray emission spectroscopy and Mossbauer effect measurements in combination.
The synthesis and study of magnetic, structure-dynamic and catalytic properties of nanocluster systems with both isolated and interacted iron oxide and other metals nanoclusters were carried out. For nanosystems of iron and other metals and their oxides in polymeric matrices, the pronounced size effects were observed. These effects were manifested itself in changing of a character of magnetic phase transitions, in an increase of critical temperature of magnetic and structure- magnetic phase transitions, in an appearance of critical size of cluster affecting first order magnetic phase transitions, in changing of atomic: and cluster dynamic as well absorption and catalytic properties.
The morphology, particle size and distribution were investigated using a high-resolution electron microscope (TEM). The estimation of media sizes of the particles gives the value 3,6*1 nm. On the other photographs a few larger particles with a media size 8*2 nm are noticed alongside with the basic particles.
The SAXS studies evidenced particles regularly dispersed in the polymer matrix with narrow log-normal size bimodal distribution centered around 3,2*0,3 nm (more than 80% particles from total quantity) and 8 nm (*1 nm).
The X-ray diffraction study showed that all samples are X-ray amorphous. This means that the size of the nano-particles is less than 10 nm.
Mossbauer spectroscopy for Fe-containing samples makes it possible to determine and to control the "phase" constitution of the composites, and also to evaluate the size of the particles.
Particle size measurement (2-10 nm) and magnetic properties showed that the material really contained the nanoparticles, which were retaining their unique properties.
Gleb Yurjevich Yurkov
Institute of General and Inorganic Chemistry, Russian Academy of Sciences
Leninsky av. 31, Moscow 119991 RUSSIA
Phone: (7-095) 954-71-36
Fax: (095) 954-12-79