- Recyclable Thermosets Based on Dynamic Amidation and Aza-Michael Addition Chemistry
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Utilizing the dynamic amidation and aza-Michael addition chemistry, a set of high strength, recyclable, and self-healable covalent adaptable networks (CANs) are synthesized by reacting the precursor and commercial oligoamine cross-linkers under mild temperature (25-50 °C) and solvent-free conditions. The amide linkages present in these CANs are readily hydrolyzable under mild acidic (pH = 5.3) conditions, whereas the aza-Michael adducts with secondary amines are thermally reversible. Utilizing the above, these CANs are depolymerized under ambient conditions in mild acidic solution and recycled with retention of original mechanical properties. The crack on the material surface is self-healed at 50 °C. The precursor, a Knoevenagel condensation product of terephthalaldehyde and diethyl malonate, is easily synthesized in a large scale. Suitable model compounds are synthesized and studied to further understand the transformations involved in the polymerization-depolymerization of these networks. These networks exhibit adequate tensile properties (ultimate tensile strength ≤35 MPa and Young's modulus ≤3 GPa), and the properties can be tuned further by suitably changing the oligoamine cross-linker. The simplicity of synthesis, cost effectiveness, adequate mechanical property, stability in aqueous and organic media, and recyclability along with self-healability render these CANs suitable for a range of applications.
- Baruah, Ranjana,Kumar, Anuj,Ujjwal, Rewati Raman,Kedia, Soumya,Ranjan, Amit,Ojha, Umaprasana
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Read Online
- Preparation method of 1,4- dibenzylidene malonic ester (by machine translation)
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The preparation method comprises the following 1,4 - steps: dissolving the terephthalaldehyde and the malonate of the formula in 1 an organic solvent; reacting 2 under the action of a catalyst; and after the reaction is 20 - 80 °C complete, the method comprises the following 3 steps 1,4 - reacting with organic acid and organic base; and reacting the reaction route as follows. In-flight vehicle R1 Sum-up table R2 An alkyl, alkenyl or 1 - 18 alkynyl group is independently selected from alkyl, alkenyl or alkynyl groups containing from about. The method provided by the invention is simple in process, short in flow, mild in reaction conditions, high in conversion rate, and capable of recycling and recycling auxiliary materials such as solvents. (by machine translation)
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Paragraph 0029-0032
(2019/12/11)
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- Sulfuric acid-modified PEG-6000 (PEG-OSO3H): A biodegradable, reusable solid acid catalyst for highly efficient and eco-friendly synthesis of novel bis-Knoevenagel products under solvent-free conditions
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Sulfuric acid-modified PEG-6000 (PEG-OSO3H) is used as a highly efficient, biodegradable, and reusable acid catalyst for the synthesis of novel acyclic and heterocyclic bis-Knoevenagel products under thermal solvent-free conditions. The remarkable features of this green, new methodology are high conversions, cleaner reaction profile, simple experimental and work-up procedure, and economic viability. The catalyst is characterized for the first time by SEM-EDX and powder XRD. The catalyst can be reused several times without significant loss of its catalytic activity.
- Siddiqui, Zeba N.,Khan, Tabassum
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supporting information
p. 3759 - 3764
(2013/07/05)
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- Meso-alkylidenyl-thia(p-benzi)porphyrins and their unusual protonation selectivity
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Meso-alkylidenyl-thia(p-benzi)porphyrin and its ring expanded analog containing exocyclic C-C double bonds at meso-positions, undergo initial protonation at the exocyclic alkylidene α-carbon.
- Jeong, Seung-Doo,Park, Kee Jong,Kim, Hyun-Jin,Lee, Chang-Hee
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supporting information; experimental part
p. 5877 - 5879
(2010/01/31)
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