Multifunctional Materials Based on Polyazomethines Derived from 2,5-Dihydroxy-1,4-Benzoquinone and Siloxane Diamines MARIA CAZACU, 1 ANGELICA VLAD, 1 GRIGORE MUNTEANU, 2 ANTON AIRINEI 1 1 ‘‘Petru Poni’’ Institute of Macromolecular Chemistry, Aleea Gr. Ghica Voda 41A, Iasi 700487, Romania 2 Chemistry Institute, Academy Street nr. 3, Moldavian Academy, Chishinew, Moldova, MD-2028 Received 5 September 2007; accepted 6 November 2007 DOI: 10.1002/pola.22531 Published online in Wiley InterScience (www.interscience.wiley.com). ABSTRACT: New polyazomethines have been synthesized by the reaction between 2,5- dihydroxy-1,4-benzoquinone and siloxane diamines differing by the siloxane sequence length. A dimer has also been prepared as a model compound. The products were char- acterized by spectral (FTIR and 1 H-NMR) and elemental analyses, GPC, viscosity measurements, solubility tests, and transmission electron microscopy (TEM). The dif- ferent properties have been investigated by adequate techniques: thermal (DSC and TGA), spectral (UV–vis and fluorescence spectroscopy), redox (Differential Pulse Vol- tammetry). pH-sensitivity and metal complexing ability were also evaluated. V V C 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1862–1872, 2008 Keywords: metal-polymer complexes; polyazomethines; redox polymers; siloxane- organic copolymers; stimuli-sensitive polymers INTRODUCTION Many studies are dedicated to polyazomethines as chelating agents or as semiconductor materi- als. 1–4 The properties of polyazomethines and their polymers depend in great measure on the kind of amine and aldehyde from which they were obtained. 5 The literature has insufficient data regarding siloxane azomethines synthesis, 6,7 even though the siloxane presence can induce some useful properties such as solubility or high gas permeability. A series of polyazomethines containing pyridine ring and oligosiloxane moi- eties has already been synthesized as macromo- lecular tridentate ligands, and complexed with cobalt to obtain highly oxygen permselective membranes. 8–10 5,5 0 -Methylene-bissalicylalde- hyde was also used as a carbonylic compound to obtain chelating polyazomethines by the reaction with siloxane diamines. 11 Dihydroxyquinones are of high interest for chemistry and biochemistry having important applications as a family of phar- maceutically active and biologically relevant chro- mophores. They are used as an analytical tool for the determination of metals, and in many aspects of electrochemistry. 12 The using of a quinone as a carbonylic partner known, as freely diffusing electron-transfer mediator in analytical sensors, would permit to obtain a new combination of inter- esting properties. Quinones are ubiquitous in elec- tron transfer chemistry and biochemistry. Thus, in electrochemistry p-benzoquinone serves commonly as aqueous redox indicator. Because of their ability to bind two protons and two electrons, quinones have many different states in terms of protonation and redox potential. It has already been reported the synthesis of polysiloxanes bearing pendant qui- none moiety as polymers having redox activity. 13 Correspondence to: M. Cazacu (E-mail: mcazacu@icmpp.ro) Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 46, 1862–1872 (2008) V V C 2008 Wiley Periodicals, Inc. 1862