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Effect of Structure of Diphenol on Polymerization of Bis(isoimide)
Published in Didier Rouxel, Sabu Thomas, Nandakumar Kalarikkal, Sajith T. Abdulrahman, Advanced Polymeric Materials, 2022
V. Sarannya, R. Surender, S. Shamim Rishwana, R. Mahalakshmy, C. T. Vijayakumar
Imide is a functional group with two acyl groups bound to nitrogen. They are less reactive, but on the other hand, commercially they are components of high-strength polymers. Many high-strength and electrically conductive polymers contain imide subunits. They are structurally related to acid anhydrides. An imide can be prepared by treating an acid anhydride with primary amine.
Carboxylic Acids, Carboxylic Acid Derivatives, and Acyl Substitution Reactions
Published in Michael B. Smith, A Q&A Approach to Organic Chemistry, 2020
An imide is the nitrogen equivalent of an anhydride and is characterized by the O=C—N—C=O moiety. How are imides named?
Preparation of a SiO x coating with a lot of micro–nanometre wrinkles on the polyimide surface and its resistance to corrosion
Published in Surface Engineering, 2021
Hulin Zhang, Xiaojuan Tian, Dan Wang, Yun Guo, Yuan Gao
Table 1 shows the tensile strength and elongation at break of Kapton substrates treated at different conditions. It is well known that the imide ring of polyimide is easily attacked by hydroxyl anions to open the ring forming an amic acid. When the alkali concentration is high enough, the amide bond is further hydrolyzed and the macromolecular chain is broken to form an amine and a diacid. For example, hydrolyzing a Kapton film with 20% NaOH will produce 80–90% of phthalic anhydride and diphenyl ether diamine. Therefore, the surface treatment of polyimide is very sensitive to the alkali concentration, and excessive hydrolysis will greatly damage its mechanical properties. For this reason, a low-concentration lye is used to treat the Kapton surface under hydrothermal conditions, at appropriate temperature and time to achieve a good surface treatment effect.
Technetium-99m metastable radiochemistry for pharmaceutical applications: old chemistry for new products
Published in Journal of Coordination Chemistry, 2019
Bianca Costa, Derya Ilem-Özdemir, Ralph Santos-Oliveira
The imido nucleus is also isoelectronic with the oxo-nucleus and functions as dianionic ligand. It is important to notice, however, that imide rarely acts as a bridging ligand and the much reduced trans-effect means that five coordination with a vacant site trans to imide is not found. Therefore, in this type of complexes, the lone pair of electrons on nitrogen is involved in the metal nitrogen multiple bonds and formally six electrons are donated to the metal. Thus, if imide is regarded as dianionic, the convention for electron counting for the metal is that it donates six electrons [40]. However the imide nucleus [99mTc═N]3+ is not stable in aqueous medium and therefore has not been explored in detail. However, the related nitride nucleus [99mTc≡N]2+ is stable to hydrolysis in aqueous medium and provides an isoelectric alternative for the [99mTc═O]3+ nucleus [38, 41]. The Tc═N bond distance of 1.704(4) Å is longer than that in [Tc0]3+ or [TcN]+2 complexes, but the Tc═NC bond angle of 171.8(4)° confirms that the imido(2–) ligand is in the linear triply bonded form [42].
Long-term thermal stability of carbon fibre-reinforced addition-type polyimide composite in terms of compressive strength
Published in Advanced Composite Materials, 2019
Yuki Kubota, Takefumi Furuta, Takuya Aoki, Yuichi Ishida, Toshio Ogasawara, Rikio Yokota
With the aim of developing new polyimide resins, Yokota et al. focused on an imide oligomer having an amorphous, asymmetric and addition-type chemical structure; the developed resins are called ‘Triple-A’ polyimides [13,14]. The chemical structure of the Triple-A polyimide series has been revised and improved several times and, at present, the most advanced Triple-A resin in the series is ‘TriA-X’, which exhibits the most advantageous properties of all the currently reported resins [15–17]. The imide oligomer of TriA-X is derived from four monomers: pyromellitic dianhydride (PMDA), 2-phenyl-4,4’-diaminodiphenyl ether (p-ODA) and 9,9-bis(4-aminophenyl) fluorene (BAFL), with 4-phenylethynylphthalic anhydride (PEPA) applied as the end cap. Figure 1 shows the chemical structure of the TriA-X imide oligomer. This imide oligomer (average degree of polymerization (n) = 4) exhibits a low melt viscosity (sufficient for composite fabrication) because its asymmetric structure suppresses aggregation (minimum melt viscosity (|η*|min) = 154 Pa·s). Further, the cured resin has a high Tg of 370 °C and an excellent failure strain (>11%), which are better than those of the addition-type polyimide resins previously reported in the literature [5,6]. Consequently, TriA-X has achieved the required combination of processability, high heat resistance and good mechanical properties, such that it is regarded as being an effective aromatic addition-type polyimide resin.