Solid Polymers Doped with Neodymium. Complex Formation and Morphology in NdCl 3 and Nd(DPM) 3 -Poly(Ethylene Oxide) Syst
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SOLID POLYMERS DOPED WITH NEODYMIUM. COMPLEX FORMATION AND MORPHOLOGY IN NdCIs AND Nd(DPM) 3-POLY(ETHYLENE OXIDE) SYSTEMS
CONOR J. TWOMEY AND SHAW H. CHEN Department of Chemical Engineering and Laboratory for Laser Energetics, University of Rochester, Rochester, NY 14627
ABSTRACT The complex formation and morphology of the NdCI 3-PEO system are presented together with some preliminary results on the Nd(DPM) 3 [Nd-tris-2,2,6,6-tetramethyl -3,5-heptane dionate]--PEO system. Although the NdCl-i-PEO complex is found to be highly hygroscopic, it is shown that residual moisture can be removed reversibly, thereby permitting the role of water in affecting the morphology of the solid to be examined. It is concluded that complexation is a competitive process between the ether oxygens on the polymer backbone and water. Under anhydrous conditions the resultant complex is amorphous at a [EOJ/[NdCI3] molar ratio approximately less than ca. 8, but above this critical value the PEO in excess of the stoichiometric ratio presents a second partially crystalline phase. The glass transition temperatures were found to increase sigmoidally with Despite the hygroscopic nature of Nd(DPM)s the resultant increasing salt content. complexes were found to be moisture resistant upon prolonged exposure to the atmosphere. INTRODUCTION The formation of solid complexes between poly(ethylene oxide), PEO, and metal salts was first reported in 1964, [1] leading to numerous investigations into a whole range of polymer-metal salt systems [2-4]. PEO and to a lesser extent poly(propylene) oxidehave been studied extensively because of the potential application of the resulting polymer complexes in the fabrication of electrochemical devices such as batteries, sensors and electrochromics. Extensive reviews of both the fundamentals and applications, primarily of alkali metal ion doped PEO, have been presented [5,6]. Other metal dopants including alkaline earth and a few other divalent metal salts have been examined from the complexation and ionic conductivity points of view [7,8]. [9] lesynthesized Furthermore, Okamoto et al. 'talý43÷ U.T3+and examined the fluorescence properties of a variety of rare earth metal-ion (eg. Eu'. Tb3, etc.) copolymer complexes containing carboxylic acid, sulfonic acid and /-diketone ligands. These studies were motivated in part by the potential usage of these complexes as plastic lasing materials. Traditional laser and magneto-optic Faraday materials consist of inorganic crystals and glasses doped with rare earth metal ions. The technological advances have been limited in part by the extremely high costs associated with materials processing and their inability to sustain high dopant concentrations without causing phase separation. Organic polymers, by nature of the tremendous versatility and flexibility in their physicochemical properties made possible by synthetic chemistry, are potentially capable of alleviating these problems. The main focus of this work is on the complex formation and morphology of PEO with NdCI3 and Nd(DPM)
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