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Keywords: A3-B3 monomers; CO2 uptake; covalent organic framework; imidization; mellitic triimide; porous polymers; polyimides; polycondensation; microporous materials This work expands the library of high-performance polyimide covalent organic frameworks (COFs) through the imidization polymerization of mellitic trianhydride with two different triamines. Among the material class of organic porous polymers, covalent organic frameworks (COFs) are a special subclass, because of their crystalline nature.[1] Moreover, depending on the building blocks, COFs can be designed with predictable pore shapes and sizes. A3-B3 monomers, CO2 uptake, covalent organic framework, imidization, mellitic triimide, porous polymers; polyimides; polycondensation; microporous materials. [Extracted from the article]

In this study, a kind of aminated poly(phthalazinone ether ketone)s (PPEK‐NH2s) with amino groups on side chains were synthesized by the condensation polymerization of 4‐(4‐Hydroxylphenyl)(2H)‐phthalazin‐1‐one (DHPZ), 4,4′‐difluoro benzophenone (DFK), and the third active monomer (4‐Amino)phenylhydroquinone (4‐AmPHQ). Then, PPEK‐NH2s were employed as compatibilizers to enhance the interfacial adhesion of carbon fiber (CF) reinforced copoly(phthalazinone ether sulfone)s (PPBES) composites. Differential scanning calorimetry and thermogravimetric analysis profiles indicate that PPEK‐NH2s exhibit more impressive thermal behaviors than PPBES. CF/PPBES composites with 5 wt% compatibilizers based on PPBES were fabricated by solution impregnation and compression molding. The as‐made CF/PPBES/PPEK‐NH2 (4) demonstrates the highest interlaminar shear strength and flexural strength with increasement of 12.7% and 16.8%, respectively. Meanwhile, this composite exhibits excellence in hydrothermal aging tests. Moreover, the strengthening mechanisms of CF/PPBES composites with PPEK‐NH2s could be attributed to both chemical and physical interaction between the matrix and CFs owing to amino groups. Therefore, these compatibilizers offer new insights for fabricating high‐performance advanced thermoplastic composites. POLYM. COMPOS., 39:4139–4147, 2018. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Phthalonitrile resins exhibit excellent thermostability and mechanical strength after curing. However, poor processability made them difficult to fabricate fiber-reinforced composites with desirable integrated performance. In this article, a novel mixed phthalonitrile resin was developed to be used as the matrix for glass fiber–reinforced laminates. Poly (aryl ether nitrile phthalazinone) oligomer end-capped by phthalonitrile units (PPEN-PN) was firstly designed and blended with bisphenol-based phthalonitrile monomers (BP-PN) (Figure 1), which were obtained according to the literature procedure. A novel mixed curing agent (zinc chloride and 4,4-diamine-diphenylsulfone) was also exploited to accelerate curing rate of the resins. Solubility tests, differential scanning calorimetry and rheological studies revealed that the mixed resins exhibited good processability with low processing viscosity. Thermal gravimetric analysis indicated that the cured resins were stable below 530 to approximately 570 °C in nitrogen atmosphere after low-cost curing procedure. In air, char yields of the resins were between 30 to approximately 40% when heated to 800 °C. The laminates reinforced by E-glass fiber cloth possessed a bending strength of 668 MPa with interlaminar shear strength of 84.6 MPa at room temperature. 50% of the strength and modulus was maintained when heated to 400 °C. Consequently, this type of laminates may be potential candidates for aerospace applications. [ABSTRACT FROM AUTHOR]

Abstract: Heat‐resistant materials have made tremendous progress in marine, aerospace and microelectronic fields. Herein, a new class of phthalonitrile resins, branched poly(biphenyl ether triphenyl‐s‐triazine) phthalonitriles, were successfully synthesized via a two‐step, one‐pot reaction, on the basis of 2,4,6‐tris(4‐fluorophenyl)‐1,3,5‐triazine and 4,4′‐biphenol. 4,4′‐Diaminodiphenylsulfone was employed to facilitate the curing reaction, and successful realization of curing behavior was concluded from rheological and differential scanning calorimetric studies, indicating the obtained resins possess favorable processability. The relationship between concentration of reactants and properties of the resins was systematically studied. After thermal curing, the E‐glass fiber‐reinforced composite, prepared with a concentration of reactants of 0.15 g mL−1, shows an admirable glass transition temperature of 480 °C and commendable thermal stability with 5% weight loss temperature in nitrogen of 563 °C, suggesting that the improvement of the thermal properties stems from the branched structure and the phenyl‐s‐triazine units. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

An epoxy based on the tetraglycidyl 4,40-diaminodiphenyl- methane (TGDDM)/bisphenol A type novolac(F-51) cured with 4,40-diaminidiphenysulfone (DDS) has been modified with Poly (phthalazinone ether nitrile ketone)(PPENK). The interaction between the PPENK and epoxy resin have been investigated by differential scanning calorimetry (DSC), FT-IR, and dynamic mechanical analysis (DMA). The thermal and mechanical properties were characterized by thermogravimetric analysis (TGA), thermomechanical analysis (TMA), flexural, impact strength, and the critical stress intensity factor tests. The results showed that a large number of physical crosslinks formed by intermolecular and intramolecular hydrogen bonding indeed existed in the TGDDM/F-51/ PPENK blends. These interactions gave good compatibility between PPENK and epoxy resin. So that any phase separation had not been detected by DMA and scanning electron microscope (SEM). Beyond that the interaction could also be a benefit to the thermal and mechanical properties. Compared with the neat epoxy resin, the critical stress intensity factor values reached the maximum at 10-phr PPENK, as well as the impact strength. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42938. [ABSTRACT FROM AUTHOR]

Matrix resin with excellent toughness finds extensive applications in structural material fields recently. In this article, phthalazinone‐bearing copoly(biphenyl ether nitrile) (PPBEN) was synthesized, followed by solution blending with commercial benzoxazine resins to enhance their toughness. The relationship between loading amount of PPBEN and combined performance of the blend system was systematically detected via the characterization of their curing behavior, thermal properties, mechanical properties, and surface morphology. The results indicated that the presence of PPBEN significantly improved the impact strength of polybenzoxazine (PBOZ) when with 10% PPBEN loading, the impact strength of PPBEN/PBOZ blends was 202% higher than that of neat PBOZ. Simultaneously, the blending system maintained a commendable flexural strength, modulus, glass transition temperature, and thermal stability. The morphology study suggested that PPBEN microparticles dispersing uniformly in bulk played an important role in releasing external energy and were responsible for final toughness during impact process. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48508. [ABSTRACT FROM AUTHOR]

Five porous ether-linked phthalazinone-based covalent triazine frameworks (PHCTFs) were successfully constructed via ionothermal polymerizations from flexible dicyano monomers containing asymmetric, twisted, and N-heterocyclic phthalazinone structure. All the building blocks could be easily prepared by simple and low-cost aromatic nucleophilic substitution reactions, showing the large-scale application potential of thermal stable phthalazinone structure in constructing porous materials. Generally, the flexible building blocks are avoided to prevent the networks from collapsing in constructing high surface area porous materials. Our experimental results revealed that the introduction of the substituents can effectively decrease the probability of the network interpenetration from the longer struts and the intermolecular/intramolecular intercalation from the increased degree of conformation freedom in the flexible ether-linkage, the BET surface areas of PHCTFs increasing from 676 to 1270 m 2 g -1 . Meanwhile, the effects of introducing different sizes (methyl or phenyl group) and amounts (one or two) of substituents on the porosities of the target polymer networks were also investigated in detail. The high CO 2 adsorption capacity of 10.3 wt % (273 K, 1 bar) can be ascribed to the strong affinity of the electron-rich N,O-containing networks with CO 2 . Excitingly, PHCTF-5 demonstrates the high CO 2 /N 2 selectivity up to 138 (273 K, 1 bar), according to the ideal adsorbed solution theory (IAST) for the higher proportion of V micro accompanied the electron-rich heteroatoms characteristic. Such high CO 2 adsorption capacity and good separation properties are superior to those of many other microporous organic polymers. These properties along with easily up-scalable synthesis make porous PHCTFs promising candidates applied in gas sorption and separation field.