Effect of the reaction conditions on the properties of poly(4,4?-diphenylether-1,3,4-oxadiazole)s

Thermally stable conducting composites based on a carbon black‐filled polyoxadiazole matrix

“…According to the literature, 9 the glass transition temperature of the POD-DPE matrix is too high (around 300 -360°C) to be processed by the usual melt blending. Therefore, the conducting mixtures studied in this work have been prepared by dispersing carbon black in a POD-DPE solution in NMP at 140°C.…”

“…This group is normally formed as the intermediary, during the synthesis of polyoxadiazole. 9 The amount of hydrazine in the POD-DPE sample synthesized in this work was in the range of 5-8%, as determined by TGA analysis. 10 The volume resistivity value of the pure POD-DPE sample was found to be 3.3 ϫ 10 7 ⍀ ⅐ cm, which corresponds to the resistivity of a semiconducting material.…”

“…9 In a typical procedure, 5 g (38.4 mmol) of HS were mixed to 250 g PPA at 150°C under stirring. Then, 10 g (38.7 mmol) of DPE were added and the medium was kept at 150°C for 4 h under stirring, in nitrogen atmosphere.…”

“…8 For example, Sena and Andrade have introduced ether groups in the polymer chain of poly(1,3,4-oxadiazole) by reacting 4,4Ј-diphenylether dicarboxylic acid and hydrazine sulphate in poly(phosphoric acid) medium. 9 The resulting poly(4,4Ј-diphenylether-1,3,4-oxadiazole) (POD-DPE) presented good solubility in formic acid and N-methyl pyrrolidone (NMP) and excellent film formation ability. These features open new possibilities of applications of these materials when good environmental and thermal stability must be associated to appropriate electrical properties.…”

Protonation of Sulfonated Poly(4,4′‐diphenylether‐1,3,4‐oxadiazole) Membranes

“…According to this procedure, the curve of protonated SPOD-DPE total area versus protonation level (Figure 3) has three segments with different slopes that might be each related to SO 2À 4 , HSO À 4 and H 2 SO 4 species. Besides the collected information, the following important literature data were taken in account to better understand the system: i) the X-ray analysis of polyoxadiazole membranes shows a bimodal distribution with intermolecular distance (d-spacing) in the range of 0.3 to 0.7 nm, [37] indicating that sulfuric acid molecules can be located between the polyoxadiazole chains; ii) the protonation is most favorable at the s lone pair of electrons which is located at both nitrogen atoms of the oxadiazole ring. The presence of the electronwithdrawing oxygen atom in the ring stabilizes the s lone pair of electrons at the nitrogen and this tends to reduce the proton affinity of this base.…”