Poly-l,3,4-oxadiazole

POLYETHERS - ETHYLENE OXIDE POLYTffiRS] (Vol 19) Poly(l,3,4-oxadiazole) (POD)... 

Poly(1,3,4-oxadiazole-2,5-diyl-vinylene) and poly(l,3,4-oxadiazole-2,5-diyl-ethynylene) were synthesized by polycondensation of fumaramide or acetylene-dicarboxamide with hydrazine sulfate in PPA to study the effect of the two repeating units on polymer electronic and thermal properties (55). 

Oxadiazoles are acquiring greater significance in the stabilizing and preparation of macromolecular materials. Thus poly-l,3,4-oxadiazoles with aliphatic substituents are used as films, although aryl derivatives can be used neither as fibres nor films. The high thermal stability of these compounds is worthy of note. 

High molecular weight aromatic poly(l,3,4-oxadiazole)s (PODS) were prepared by a one-pot procedure from dicarboxyhc acid and a hydrazine salt (sulfate, phosphate) or dicarboxylic acid dihydrazides in a mixture of ionic liquid and triphenyl phosphate, used both as a solvent and condensing agent. The polycyclization occurred at a sufficiently low temperature of 210 °C to give film-forming PODS [92]. 

A review of the preparation of the aromatic poly-l,3,4-oxadiazole appears in Vol. I of this series [28]. 

The aliphatic poly-l,3,4-oxadiazoles are made by a similar process by the thermal reaction of the polyhydrazides. 

B. Schulz, M. Bruma, andL. Brehmer. Aromatic poly(l,3,4-oxadiazole)s as advanced materials. Adv. Mater., 9 601-613,1997. 

R. Zhang, R. Jordan, and 0. Nuyken. Preparation of poly(l,3,4-oxadiazole-2,5-diyl-l,2-vinylene) via anionic mechanism. Macromol. Rapid Commun., 24 246-250, 2003. 

Poly(2-methoxy-5-(3, 7 -dimethyloctyloxy)-l,4-phenylene vinylene), 117 Poly(2-methoxy-5-(2 -ethylhexyloxy)-l,4-phenylene vinylene), 31, 50, 91, 117 Poly(methyl-bis-(3-methoxyphenyl)-(4-propylphenyl)amine)siloxane, 42 Poly(methyl methacrylate), 32, 41, 100, 341, 499 Poly(2-methyl-5-vinyl)tetrazole, 319 Poly(l,5-naphthylene vinylene), 98 Poly(l,3,4-oxadiazole), 329 Poly(l,3,4-oxadiazole-2,5-diyl-l,2-vinylene), 337... 

Several attempts have been made to develop sulfonated polyazoles [148, 149] and polybenzazoles [150-160]. Sulfonated poly-l,3,4-oxadiazoles have been prepared by the interaction of 5-sulfoisophthalic acid with hydrazine sulfate in polyphosphoric acid (PPA) [148,149]... 

Poly(l,3,4-oxadiazole aryl etherjs can be synthesized as shown in Figure 10.8. 

The electrochemical fluorescence switching from a patternable poly(l,3,4-oxadiazole) thin film has been assessed [46]. The high solubility of the polymers enables a simple fabrication of an electrochemical cell, which shows a reversible fluorescence switching between dark and bright states with a maximum on/off ratio of 2.5 and a cyclability longer than 1000 cycles. The photochemical cleavage of the oxadiazole in the poly(arylene-l,3,4-oxadiazole) allows a photo-patterning of the film upon exposure to UV source. 

More AS, Menon SK, Wadgaonkar PP. New poly(l,3,4-oxadiazole)s bearing pentade-cyl side chains synthesis and characterization. J Appl Polym Sci 2012 124(2) 1281-9. 

Pradeep K, Venugopala Reddy K, Harish M, Chidananda B, Madhu B, Mruthyunjayachari C, et al. Poly(l,3,4-oxadiazole-aryl ether) embedded metalphthalocyanines synthesis, characterization and electrical studies. Synth Met 2013 185-186 79-88. 

Seo S, Kim Y, You J, Sarwade BD, Wadgaonkar PP, Menon SK, et al. Electrochemical fluorescence switching from a patternable poly(l,3,4-oxadiazole) thin film. Macromol Rapid Commun 2011 32(8) 637 3. 

Hsiao SH, Wang HM, Guo W, Sun CH. Enhancing redox stability and elec-trochromic performance of polyhydrazides and poly(l,3,4-oxadiazole)s with 3,6-di-tert-butyl-carbazol-9-yltriphenylamine units. Macromol Chem Phys 2011 212(8) 821-30. 

Zhou W, Yang X, Jia E, Wang X, Xu J, Ye G. Ultraviolet resistance of azo-containing poly(l, 3,4-oxadiazole) fibres. Polym Degrad Stab 2013 98(3) 691-6. 

Hamciuc C, Hamciuc E, Serbezeanu D, Vlad-Bubulac T. Thermal and optical properties of some phosphorus-containing poly(l,3, 4-oxadiazole-ester-imide)s. Polym Adv Tech-nol 2011 22(12) 2458-68. 

Aromatic polymers with phosphonated sites directly linked to the main chain have also been prepared by direct polymerization (Scheme 13.2a-d). For example, phosphonated poly(l,3,4-oxadiazole)s have been prepared by direct polycondensation of l,4-dicarbo3y-2-phenyl-phosphonic acid and their dihydrazides in an ionic liquid using triphenyl phosphite as a reaction activator. " The membranes obtained from these polymers were thermally and chemically stable and possessed proton conductivities in the range between 4x10 " and 5x10 mS cm at 100% RH, which is three orders of magnitude lower than the state-of-the-art PFSA membrane Nation . 

Hamciuc, E. Hamciuc, C. Cazacu, M., Poly(l,3,4-Oxadiazole-ether-imide)s and Their Polydimethylxiloxane-Containing Copol)miers. Eur. Polym. J. 2007, 43, 4739-4749. 

Hsiao SH, Chiou JH (2001) Aromatic poly(l,3.4-oxadiazole)s and poly(amide-l,3,4-oxadiazole) s containing ether sulfone linkages. J Polym Sci A Polym Chem 39 2271-2286... 

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