Poly layered intercalate

The inner structure of polyelectrolyte multilayer films has been studied by neutron and X-ray reflectivity experiments by intercalating deuterated PSS into a nondeut-erated PSS/PAH assembly [94, 99]. An important lesson from these experiments is that polyelectrolytes in PEMs do not present well-defined layers but are rather interpenetrated or fussy systems. As a consequence, polyelectrolyte chains deposited in an adsorption step are intertwined with those deposited in the three or four previous adsorption cycles. When polyelectrolyte mobility is increased by immersion in NaCl 0.8 M, the interpenetration increases with time as the system evolves towards a fully mixed state in order to maximize its entropy ]100]. From the point of view of redox PEMs, polyelectrolyte interpenetration is advantageous in the sense that two layers of a redox polyelectrolyte can be in electrochemical contact even if they are separated by one or more layers of an electroinactive poly ion. For example, electrical connectivity between a layer of a redox polymer and the electrode is maintained even when separated by up to 2.5 insulating bUayers [67, 101-103]. 

Pantoustier, N., Alexandre, M., Degee, P, Calberg, C., Jerome, R., Henrist, C., et al. (2001). Poly(3-caprolactone) layered silicate nanocomposites effect of clay surface modifiers on the melt intercalation process. e-Polymer, 9, 1-9. 

Batteries. Many 7t-conjugated polymers can be reversibly oxidized or reduced. This has led to interest in these materials for charge-storage batteries, since polymers are lightweight compared to metallic electrodes and liquid electrolytes. Research on polymer batteries has focused on the use of polymers as both the electrode and electrolyte. Typical polymer electrolytes are formed from complexes between metal-ion salts and polar polymers such as poly(ethyleneoxide). The conductivity is low at room temperature due to the low mobility of cations through the polymer-matrix, and the batteries work more efficiendy when heated above the glass-transition temperature of the polymer. Advances in the development of polymer electrolytes have included polymers poly(ethylene oxide) intercalated into layered silicates (96). These solid-phase electrolytes exhibit significantly improved conductance at room temperature. 

Layered silicate clays intercalated by pillaring poly-oxocations are precursors to an important class of mi-croporous catalysts. Smectite clay was the only host structure known to be pillarable by purely inorganic oxo ions. Recently, layered double hydroxides (LDH) pillaring oxo ions were reported by Pinnavaia and coworkers [79, 80]. 

Fig. 18. The steady-shear rheological behavior for a series of intercalated nanocomposites of poly(dimethyl0 95-diphenyl0 05siloxane) with layered silicate (dimethyl ditallow montmo-rillonite) at 25 °C. The silicate loading is varied and are noted in the legend. From Ref. [5].

Intercalation of poly(ethylene oxide) into a lithium-ion exchanged clay gives an interesting class of layered silicate nanocomposites that are lithium-ion electrolytes. Componnds have been prepared by intercalation from methanol/water solutions and by melt intercalation. Melt intercalation typically gives samples with higher polymer contents than the solution method and with higher lithium-ion conductivity though the conductivity is probably stiU too low for practical applications. 

Intercalation of organic molecules into layered host lattice produces a variety of organic-inorganic hybrid materials. The solvothermal method provides a reaction system that allows application of high temperatures and therefore is a powerful technique for preparation of intercalation compounds. Exfoliation of layers may occur because of applied high temperatures. For example, exfoliated poly-ethylene/montmoriUonite nanocomposites were reported to be prepared by solvothermal reaction of organophilic montmorillonite with polyethylene in toluene at 170°C for 2... 

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