Synthesis, characterization, and properties of polymer/inorganic layered host nanocomposites

Abstract

A novel method was found and developed to prepare hybrid polymer/inorganic layered host nanocomposites. The effect of incorporation of polymer on the cation mobility and the performance of some of these novel materials as cathodes in secondary lithium batteries were examined using electrochemical and solid state NMR methods. A mode couplingtheory with extension was introduced to explain the spin-lattice relaxation mechanisms of polymer/inorganic nanocomposites, which, the author believes, can be extended to any system containing a submotional phase which may be the source of different relaxation mechanisms.

A (PPY)o.5MoO3 nanocomposite was prepared by a new method, namely, an oxidative polymerization/ion exchange method. The large d-spacing increase (7.0A) evidenced by XrD was explained by a hydrogen bonding model. FTIR and conductivity data suggested a conductive form of PPY in (PPY)o.5MoO3. The increased conductivity of this nanocomposite, heated at 200oC, was explained as the further polymerization of oligomer within the MoO3 gallery.

By controlling the degree of swelling of MoO3xi sheets with various ratios of Li/Na in the molybdenum bronze and by using mixed solvents, both the monolayer (PEO)0.4NaMoO3 and bilayer (PEO)0.9(Li,Na)MoO3 nanocomposites were isolated. A model based on XRD, 13C/23Na solid state NMR and FTIR data was proposed for the structure of the monolayer and bilayer nanocomposites. 7Li/23Na solid state NMR spin-lattice relaxation and linewidth studies on bilayer (PEO)0.9(Li,Na)MoO3 nanocomposites show different relaxagtion mechanisms in different temperature regions; these were explained by a mode coupling theory with extension. A comparative study of the electrochemical insertion of lithium into the two polymer nanocomposites and NaMoO3 by using the materials as cathodes in rechargeable lithium batteries indicate that the kinetics of the electrochemical Li insertion/deinsertion process is improved by incorporation of the polymer.

(PANI)0.4a-Sn(HOPO3)2 and (PPV)3.0a-Sn(HOPO3)2 were prepared either by an acid-base reaction or an ion exchange reaction. (PPV)3.0a-Sn(HOPO3)2 represents the first example of direct insertion of a polymer into a metal phosphate by ion-exchange. While the (PANI)0.4a-Sn(HOPO3)2 exhibit low but measurable conductivity, (PPV)1.0a-Sn(HOPO3)2 behaves as an insulator.