Bisphthalonitrile Monomer Research Articles

Effect of Phosphate-Bridged Monomer on Thermal Oxidative Behavior of Phthalonitrile Thermosets.

Phthalonitrile thermosets are known for their excellent mechanical, physico-chemical, and fire-retardant properties, making them attractive for aerospace and mechanical engineering applications. When producing and applying phthalonitrile-based structural parts, it is essential to consider aspects such as processability and the long-term stability of the material's properties at high temperatures. In our previous studies, we demonstrated that resins containing phosphate-bridged bisphthalonitrile monomers are easily processable due to their low melting temperature and wide processing window. In this study, we investigated the impact of bis(3-(3,4-dicyanophenoxy)phenyl)phenyl phosphate (PPhPN) monomer content on physico-chemical and mechanical properties, thermal stability, and thermal oxidative stability. This research highlights the importance of conducting long-term thermal oxidative aging studies in addition to thermogravimetric analysis to properly assess the stability of thermosets. The findings indicate that adding less than 15% of PPhPN results in the formation of a crystalline phase, which impairs the resin's processability. Conversely, a high PPhPN content reduces the material's thermal oxidative stability. Therefore, based on mechanical and physico-chemical tests after thermal oxidative aging, it can be concluded that a 10-15% concentration of the phosphate-containing monomer enables easy processability of the phthalonitrile resin and provides excellent long-term thermal oxidative stability at temperatures up to 300 °C, while maintaining a flexural strength exceeding 120 MPa and an elasticity modulus of 4.3 GPa.

Advanced composites based on end-capped polyarylene ether nitrile/bisphthalonitrile with controllable thermal curing reaction

A novel polymer was prepared through the combination of phthalonitrile end-capped polyarylene ether nitrile (PEN-Ph) and bisphthalonitrile (BPh), applying post-solid phase chemical reaction technology. BPh monomer was firstly pre-polymerized to form BPh prepolymer and then followed by crosslinking reaction with PEN-Ph matrix resin to obtain PEN-Ph/BPh composites. The generated crosslinking structures were confirmed by FTIR and UV including phthalocyanine, triazine, and isoindoline rings. Besides, the effect of BPh pre-polymerization time on the performance of PEN-Ph/BPh composite materials was studied. Tensile strength and modulus highest values of composites exceeded 98.9 MPa and 2.17 GPa respectively as BPh pre-polymerization time reached 30 min, improved by 55.6% and 36.9% in comparison with unpolymerized one. Besides, PEN-Ph/BPh composite films exhibited superior thermal properties (Tg: 278–330 °C, T5% (decomposition temperature of 5 wt%)>500 °C) and maintained excellent dielectric stability over 300 °C, leading to use for electronic fields at elevated temperature.

Novel low-melting bisphthalonitrile monomers: Synthesis and their excellent adhesive performance

High melting temperature of most bisphthalonitrile monomers are a challenging problem in processing, especially for the preparation of adhesives. The present work introduces the “asymmetric structure” concept to improve the processability of bisphthalonitrile. Four novel bisphthalonitrile monomers (BBPN, BCPN, BPPN, and BMPN) with relatively low melting points were synthesized by a nucleophilic substitution reaction, and FTIR, 1H, and 13C NMR analysis were performed for the confirmation of chemical structures. A much lower melting point and broader processing window as compared to 4,4′-bis(3,4-dicyanophenoxy)biphenyl (BAPh) were recorded for the synthesized monomers. Then they were cured by using 8 wt% of p-phenylenediamine (p-PD) as a curing agent, and backbone structures of monomers played a vital role in the glass transition temperature (Tg) and recorded in between 255 and 311 °C. The incorporation of asymmetric structure results in an amazing adhesive performance, which is comparable with commercial polyimides but coupled with a thermal stability tradeoff.

Curing kinetics and thermal properties of imide containing phthalonitrile resin using aromatic amines

Due to their outstanding properties, phthalonitrile based polymers plays an important role in high performance advanced materials evaluated depending upon their curing process and mechanism. Henceforth it is necessary to understand the curing kinetics of bisphthalonitrile monomer having imide linkage using 4, 4’-diaminodiphenylsulfone (DDS) as curing agent for further investigations. Thus, curing kinetics was investigated by recording non-isothermal differential scanning calorimetric (DSC) scans at heating rates of 5 °C, 10 °C, 15 °C and 20 °C/min. Activation energy for bisphthalonitrile/4, 4’-diaminodiphenylsulfone (DDS) system was calculated using Starink method and results give a substantial evidence that Arrhenius activation energy (Ea) are certainly dependent on the structure of monomer and curing agent. The cured FIPN/DDS, ODPA-PN/ DDS systems show comparable high thermal stability and elevated glass transition temperature as compared to Bis-ADPN/ DDS composition. Subsequently, this composition exhibits comparative heat resistance and improved moisture resistance.

Curing kinetic of self-promoted alicyclic-based bisphthalonitrile monomer

Self-promoted alicyclic-based phthalonitrile possesses outstanding properties, which would be determined by the special free radical curing mechanism and curing process. Thus, the curing kinetic of alicyclic-based phthalonitrile was studied and the curing kinetic parameters were determined by DSC at various heating rates. Double fit peaks were used to analyze the reaction processes. The autocatalytic model based on Šesták–Berggren model of DAIM-PN was confirmed. Moreover, the predicated models of DAIM-PN could fit well with the experimental values.

Studies on crosslinking and thermal behavior of phthalonitrile end‐capped imide monomer in presence of aromatic amines

ABSTRACTThis paper describes the synthesis and characterization of a bisphthalonitrile monomer having an imide linkage prepared by reacting 4,4′‐(hexafluoroisopropylidene) diphthalic anhydride with 4‐(4‐aminophenoxy) phthalonitrile. The structure of the monomer was confirmed by Fourier transform infrared, 1H‐NMR, and 13C‐NMR spectroscopy. The curing behavior of bisphthalonitrile monomer was investigated in the absence or presence of different diamines using differential scanning calorimetry. Diamines 4,4′‐diaminodiphenyl ether (DDE) and 4,4′‐diaminodiphenylsulfone (DDS) were used to investigate the effect of the structure of diamines on the curing behavior of bisphthalonitrile monomer. An exothermic transition due to curing was observed in the DSC scan, and the curing temperature was found to be dependent on the nucleophilicity of the amine. DDE was found to be more reactive than DDS. The thermal stability of the cured resins was evaluated using thermogravimetry in nitrogen atmosphere. All of the cured samples were stable up to 400 °C and leave behind 62% char residue at 800 °C, which was found to be dependent on the structure of the diamine used for curing as well as on the curing conditions. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46151.

Copolymerization of bisphthalonitrile/benzoxazine blends: Curing behavior, thermomechanical and thermal properties

A high-performance copolymer was successfully prepared by blending bisphenol-A based bisphthalonitrile monomer (BAPh) with phenol-aniline-based benzoxazine monomer (P-a). The obtained copolymers exhibited excellent thermal stability and thermomechanical properties. The Fourier transform infrared (FTIR) spectra of BAPh/P-a 5:5 system at different curing procedure proved the curing reaction mechanism. In addition, differential scanning calorimetry (DSC) curves showed that the curing reaction of the BAPh was induced by the active hydroxyl produced by the ring-opening polymerization of P-a; compared to the neat monomers, the curing temperature of the copolymer decreased and the curing speed improved. The evolution of thermal gravimetric analysis (TGA) curves revealed that the poly(BAPh/P-a)-5:5 displayed highest T5%, T10%, and char yield. The dynamic mechanical analysis (DMA) proved that the glass transition temperature and storage modulus of copolymers with the BAPh monomer as the matrix increased with the content of P-a increase, while copolymers with P-a as the matrix obtained nearly same results. The poly(BAPh/P-a) -5:5 exhibited best thermal and thermomechanical properties among different composition copolymers.

Synthesis, curing kinetics and thermal properties of a novel self-promoted fluorene-based bisphthalonitrile monomer

A novel amino-containing fluorene-based bisphthalonitrile monomer, 9,9-bis(4-aminophenyl)-2,7-(3,4-dicyanophenoxy)-fluorene (AFPN), was successfully synthesized via the nucleophilic displacement of the nitro-substituent from 4-nitrophthalonitrile. The structure of AFPN was confirmed by Fourier transform infrared (FT-IR), 1H and 13C nuclear magnetic resonance (NMR). Its curing behavior and curing kinetics were investigated using differential scanning calorimetry (DSC) and FT-IR techniques. Isoconversional method based on Starink was applied to analyze the curing process of AFPN. The thermal and mechanical properties of the cured product were evaluated by thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The AFPN showed a self-promoted curing behavior, whereas the introduction of the amino groups increased its curing rate and lowered its curing temperature. Additionally, its cured polymer showed an excellent thermal and thermo-oxidative stability, since its char yield reached 76.5% at 800°C in nitrogen and 83.4% at 600°C in air, respectively.

Synthesis, polymerization, and properties of the allyl‐functional phthalonitrile

ABSTRACTA novel bisphthalonitrile monomer containing allyl groups (DBPA‐Ph) had been synthesized via the reaction of diallyl bisphenol A (DBPA) and 4‐nitrophthalonitrile. The chemical structure of DBPA‐Ph was confirmed by 1HNMR, 13CNMR, and FTIR spectroscopy. The curing behaviors and processability of DBPA‐Ph were studied by differential scanning calorimetry (DSC) and dynamic rheological analysis. The monomer manifested a two‐stage thermal polymerization pattern. The first stage was attributed to the polymerization of allyl groups and the second to the ring‐form polymerization of cyano groups. The result of dynamic rheological analysis indicated the monomer had wide curing window and the self‐catalyzed curing behavior. DBPA‐Ph polymers were prepared from the thermal polymerization with short curing time, showing high glass transition temperature (>350°C) and attractive thermal decomposition temperature (>430°C). The outstanding glass transition temperature, desirable thermo‐oxidative stabilities, good processability and sound process conditions could provide more applications to the DBPA‐Ph polymers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41203.

Preparation and thermal properties of novel phthalonitrile oligomer containing biphenyl ethernitrile/bisphthalonitrile blends

AbstractA kind of novel n = 2 phthalonitrile oligomer containing biphenyl ethernitrile (2PEN‐BPh) had been firstly synthesized from 2,6‐dichlorobenzonitrile, 4,4′‐biphenol and 4‐nitrophthalonitrile via solution reaction, and the 2PEN‐BPh was characterized by FTIR, 1H‐NMR spectra which exhibited that cyano groups and ethernitrile linkages existed in the backbone of 2PEN‐BPh. The 2PEN‐BPh oligomer was blended with bisphthalonitrile monomer, the curing reaction behaviors of the blends were studied by FTIR, DSC, and rheological analysis. The thermal and thermo‐oxidative stabilities of the 2PEN‐BPh/BPh polymers were investigated by TGA, and the results showed that the completely cured polymers could achieve char yields up to 78% at 800°C in nitrogen, above 11% at 800°C in air. The whole research indicated that the 2PEN‐BPh/BPh blends could efficiently improve the processability of BPh monomer without scarifying other desirable high temperature properties. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Synthesis and curing behavior of a novel benzoxazine‐based bisphthalonitrile monomer

AbstractA novel bisphthalonitrile containing benzoxazine units (BZ‐BPH) was synthesized via a solventless method from 4,4′‐dihydroxybiphenyl, paraformaldehyde, and 4‐aminophenoxylphthalonitrile. The chemical structure of BZ‐BPH was confirmed by 1H‐NMR and 13C‐NMR analyses. The curing behavior was investigated with DSC, FTIR, TGA, and rheology techniques. The monomer manifested a two‐stage thermal polymerization pattern. The first stage was attributed to the ring‐opening polymerization of benzoxazine moiety, and the second to the polymerization of phthalonitriles. Study about the effect of the catalysts including 4,4′‐diaminodiphenylsulfone and FeCl3 on the polymerization of BZ‐BPH was performed, and the result indicated that the addition of these agents could increase the curing rate and lower the curing temperature. Additionally, the cured product showed excellent thermal and thermo‐oxidative stability, the high char yield was 76.0% by weight at 800°C in nitrogen atmosphere and 81.2% by weight at 600°C in air, and temperature at 5% weight loss (T5%) in nitrogen and air was 477.9°C and 481.7°C, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Microporous Network Polymers Based on Cobaltphthalocyanines

AbstractA series of microprous Co‐phthalocyanine based plolymers were prepared in good yield (>90%) by the polymeric tetramerisation reaction of nonplanar bisphthalonitrile monomers with cobalt acetate. The resulting free‐flowing polymers are dark green in apperance with good stability towards a range of solvents and temperature. High Resolution Transmission Electron Microscopy image clearly shows the presence of micropores (<2 nm). Nitrogen adsorption/desorption measurements show that these materials have high surface areas in the range of 500–600 m2g−1 along with high concentration of pores in the range of 0.6–0.7 nm.

Synthesis and characterization of new monomeric and polymeric phthalocyanines

AbstractMonomeric (M = 2Li or 2H) and polymeric (M = 2H, Zn, Cu, Co, or Ni), where M is metal or hydrogen, phthalocyanines were prepared by the tetramerization reaction of bisphthalonitrile monomer with appropriate materials. The electrical conductivities of the polymeric phthalocyanines, which were measured as gold sandwiches, were found to be 10−10–10−7 S/cm in vacuo and in air. The binding property of a Co‐containing polymeric phthalocyanine (10) toward alkali, alkaline‐earth, and some heavy cations was studied in tetrahydrofuran. The extraction affinity of 10 for K+ was found to be the highest in the heterogeneous phase extraction experiments. The disaggregation property of a Ni‐containing polymeric phthalocyanine (11) was investigated with K+, Na+, and NH4+ cations. The intrinsic viscosities of all polymers were also measured by means of viscometry. All the novel compounds were characterized with elemental analysis, ultraviolet–visible, Fourier transform infrared, NMR, and mass spectrometry spectral data, and differential thermal analysis/thermogravimetry. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Novel phthalocyanine polymers with very flexible pentathiatetraethylene units

A series of polymeric metal-free and metallophthalocyanine (M = 2H, Ni, Co, Fe, Pb, Cu and Zn) polymers were prepared by polymeric tetramerization reaction of bisphthalonitrile monomer with proper materials. The Co–phthalocyanine polymer was prepared by two different methods. The metal-free ( 3) and the Co-containing phthalocyanine polymer ( 5) were chemically doped with iodine (I 2) and nitrosyl tetrafluoroborate (NOBF 4), respectively. The electrical conductivities of the polymeric phthalocyanines measured as gold sandwiches were found to be 10 −8–10 −4 S cm −1 in vacuum and in argon. The electrical conductivities of I 2-doped metal-free phthalocyanine ( 3a) and NOBF 4-doped Co–phthalocyanine ( 5a) polymers were found to be approximately 110 and 89 times higher than those of undoped versions, respectively. The extraction ability of 3 was also evaluated in tetrahydrofuran using several transition metal picrates such as Ag +, Hg 2+, Pb 2+, Cd 2+, Cu 2+ and Zn 2+. The extraction affinity of 3 for Ag + was found to be highest in the heterogeneous phase extraction experiments. The aggregation and disaggregation properties of 3 were investigated with silver(I), mercury(II) and methanol as solvent. All the novel compounds were characterized by using elemental analysis, UV–vis, FT-IR, NMR and MS spectral data and DTA/TG.

Investigation of the Properties of Phthalocyanine Resin Containing Bismaleimide Groups

A bisphthalonitrile monomer containing bismaleimide groups was synthesized using 4,4′-bismaleimidodiphenylmethane and 4-aminophenoxyphthalonitrile. The structure of the monomer was confirmed by elemental analysis and IR spectroscopy. With this monomer, a phthalocyanine resin containing bismaleimide groups was obtained by catalytic thermal polymerization. The structure of the resin was confirmed by IR spectroscopy. The characteristic absorption peak of nitrile groups at 2200cm-1 disappeared in the IR spectra, showing that polymerization of monomer was complete. Thermogravimetry of the resin in air and N2 was investigated; the results show that this resin has excellent thermal and thermo-oxidative stabilities, and a high char yield in nitrogen (82·7%). In addition, a monomer solution in dimethylacetamide was flow-coated on a glass strip to form a resin film. The adhesion between film and glass strip was firm, and the resin film had strong resistance to saturated alkali solution. A solubility test showed that the resin possessed good chemical inertness. Copper and aluminium strips were bonded using monomer solution. The single-lap shear strength of samples was tested after curing. The results demonstrated that the adhesion between resin and copper strips was stronger than with aluminium strips. The resin can be used as a heat-resistant adhesive. © of SCI.

Synthesis and characterization of the novel type of polymerizable bisphthalonitrile monomers

AbstractThree new bisphthalonitrile derivatives are prepared by the nucleophilic displacement of the nitrosubstituent from 4‐nitrophthalonitrile with 9,9‐bis(4‐hydroxyphenyl)fluorene; 9,9‐bis(3,5‐dimethyl‐4‐hydroxyphenyl)fluorene, and phenolphthalein in the presence of potassium carbonate. The reaction has been carried out in dimethylsulfoxide solvent. These monomers are characterized by elemental analysis, FT‐IR, 1H NMR, TGA, DSC, and mass spectral studies. A tentative mechanism for the fragmentation of the compounds is given to explain the mass spectral data. The compounds are expected to be useful to prepare thermally stable thermosetting phthalocyanine polymers.

Electrically conducting polymers from conjugated bis‐phthalonitrile monomers

AbstractElelectrically conducting polymers have been synthesized from completely conjugated bisphthalonitrile monomers. The monomers melt and are thermally polymerized at 260–300°C in air and then are converted into conductive materials by further processing at elevated temperatures in an inert atmosphere. Because the monomers remain in a liquid stage for 1–2 h, depending on the cure conditions, moldings, castings, and pre‐pregs can be fabricated using conventional processing techniques. The conductivity can be varied from that of an insulator to approximately 10+2(Ωh cm)−1. For example, after a 600°C treatment, the conductivity is approximately 1(Ω cm)−1. Since reactive dopants are not used, the material and conductivity are stable in ambient as well as more aggressive environments, allowing them to function at 300°C and above. The monomers are well characterized, but the structure of the cured and postcured polymers are not yet well defined because of their high stability and intractability in the cured state.

Network structure in bisphthalonitrile polymers

Bisphthalonitrile monomers were cured neat, with nucleophilic and redox coreactants, or in combination with a monofunctional model compound. Dynamic mechanical measurements on the resulting polymers from −150°C to +300°C turn up several differences attributable to differences in network structure. Rheovibron results were supplemented with solvent extraction, DSC, vapor pressure osmometry, and infrared spectroscopy to characterize the state of cure.

Synthesis and characterization of polymerizable bisphthalonitrile monomers

AbstractThe reactions of 4‐aminophthalonitrile (APN) with 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BPTDA), and with 1,2,3,4‐benzenetetracarboxylic dianhydride (PMDA) have been studied to optimize the conditions for the synthesis of monomeric thermosetting bisphthalonitrile compound. Suitable procedures for the synthesis of the two monomers are presented. Elemental analyses, IR spectra, dynamic thermogravimetric analyses, differential scanning calorimetry, 1H‐NMR, and mass spectral studies have been used to characterize these compounds. Preliminary observations show that these materials can be polymerized to give high‐temperature‐resistant materials.