Hafnium-containing Nanocomposites

Abstract

Hafnium-containing nanocomposites are prepared using polymermediated synthesis and controlled thermolysis. The new types of Hf-containing monomers and polymers were synthesized. The composition and structure of the synthesized hafnium-containing precursors and thermolysis products are determined by elemental analysis, IR spectroscopy, mass spectrometry, optical and scanning electron microscopies, and x-ray diffraction. Thermodynamic analysis is used to assess the equilibrium composition of the Hf-C-H-O system and establish the conditions under which HfC and HfO 2 are formed.

Nanostructured Materials Preparation via Condensation Ways

“…Currently, there are three key methods for the preparation of metallopolymers [365] for polymer-mediated synthesis of nanoparticles: reactions of metal compounds This fact will be demonstrated in relation to hafnium-containing polymers obtained by polymer analogous transformations involving PAA (compound 1), by condensation methods, viz., the reaction of hafnium compounds with diols (2-6) or condensation of cyclopentadienyl hafnium complexes with p-diethynylbenzene (7), and by polymerization of hafnium-containing monomers (8)(9)(10)(11)(12) [500][501][502]. The isothermal thermolysis of Hf(IV) -polymer systems (1-12) was studied at three characteristic temperatures: 1) 643 K (heating for 60-300 min) À the mean decomposition temperature where secondary transformations (pyrolysis of the decomposition products) are insignificant; 2) 873 K (150-200 min) -the mean temperature of the early stages of pyrolysis of the organic transformation products; 3) 1,273 K (~150 min) -the temperature of intense pyrolysis of organic products.…”

Refractory Metal‐Containing Polymers and Nanocomposites: Preparation and Properties

“…Traditionally these materials have been prepared by high temperature powder techniques that are limited in their ability to generate homogeneous systems with controlled compositions and properties. We have elaborated a novel approach that employs metal‐containing monomer and metallopolymer precursor routes to such materials 1–5. It comprises; (i) thermal transformations of metal‐containing monomers (MCM); i.e., compounds comprising a metal equivalent and a polymerisable group containing multiple bonds, involving solid‐state (co)polymerization of the monomers (ii) thermolysis of the metallopolymers formed to generate nanoparticles stabilized with a polymer matrix.…”