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A diamine monomer, 4,4’-bis(5-amino-2-pyridinoxy)benzophenone, was designed and synthesized, and used to react with commercially different kinds of aromatic dianhydrides to prepare a series of polyimides containing pyridine and ketone units via the classical two-step procedure. Glass transition temperatures (Tg) of the resultant polyimides PI-(1–5) derived from 4,4’-bis(5-amino-2-pyridinoxy) benzophenone with various dianhydrides ranged from 201 to 310 °C measured by differential scanning calorimetry. The temperatures for 5%wt loss of the resultant polyimides in nitrogen atmosphere obtained from the thermogravimetric analysis curves fell in the range of 472–501 °C. The temperatures for 10%wt loss of the resultant polyimides in nitrogen atmosphere fell in the range of 491–537 °C. Meanwhile, the char yields at 800 °C were in the range of 55.3–60.8%. Moreover, the moisture absorption of polyimide films was measured in the range of 0.37–2.09%. The thin films showed outstanding mechanical properties with tensile strengths of 103–145 MPa, an elongation at break of 12.9–15.2%, and a tensile modulus of 1.20–1.88 Gpa, respectively. The coefficients of thermal expansion of the resultant polyimides were obtained among 26–62 ppm °C−1. To sum up, this series of polyimides had a good combination of properties applied for high-performance materials and showed promising potential applications in the fields of optoelectronic devices.

Two series of isomers containing pyridine and sulfur unit aromatic diamine monomers, 4,4′-bis(5-amino-2-pyridinylsulfanyl)diphenyl sulfide ( 2a), 4,4′-bis(6-amino-3-pyridinylsulfanyl)diphenyl sulfide ( 2b) and 4,4′-bis(5-amino-6-methyl-2-pyridinylsulfanyl)diphenyl sulfide ( 2c), 4,4′-bis(5-amino-4-methyl-2-pyridinylsulfanyl)diphenyl sulfide ( 2d), were designed and synthesized. Aimed at clarifying the structure-property relationships of pyridine- and sulfur-containing high refractive polymers, 2a was polymerized with various dianhydrides to prepare polyimides PI-1− PI-7 and 2b, 2c, 2d were reacted with 4,4′-[ p-thiobis(phenylenesulfanyl)]diphthalic anhydride to prepare polyimides PI-8− PI-10. The polyimides showed excellent optical properties with average refractive indices ranging from 1.7006 to 1.7620 and birefringence as low as 0.0056. Meanwhile, comparative studies on their properties including solubility, thermal and mechanical, and optical transparency properties were performed. Some property differences of the isomers caused by the sequence changes were found. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

A diamine monomer, 4,4’-bis(5-amino-2-pyridinoxy)benzophenone, was designed and synthesized, and used to react with commercially different kinds of aromatic dianhydrides to prepare a series of polyimides containing pyridine and ketone units via the classical two-step procedure. Glass transition temperatures (Tg) of the resultant polyimides PI-(1–5) derived from 4,4’-bis(5-amino-2-pyridinoxy) benzophenone with various dianhydrides ranged from 201 to 310 °C measured by differential scanning calorimetry. The temperatures for 5%wt loss of the resultant polyimides in nitrogen atmosphere obtained from the thermogravimetric analysis curves fell in the range of 472–501 °C. The temperatures for 10%wt loss of the resultant polyimides in nitrogen atmosphere fell in the range of 491–537 °C. Meanwhile, the char yields at 800 °C were in the range of 55.3–60.8%. Moreover, the moisture absorption of polyimide films was measured in the range of 0.37–2.09%. The thin films showed outstanding mechanical properties with tensile strengths of 103–145 MPa, an elongation at break of 12.9–15.2%, and a tensile modulus of 1.20–1.88 Gpa, respectively. The coefficients of thermal expansion of the resultant polyimides were obtained among 26–62 ppm °C−1. To sum up, this series of polyimides had a good combination of properties applied for high-performance materials and showed promising potential applications in the fields of optoelectronic devices. [ABSTRACT FROM PUBLISHER]

Polyimides (PIs) are widely applied in the fields of aerospace, membrane, and electronic industries. However, with the fast-growing application, the degradation of polymer has become a serious problem people are confronted with. In this work, a series of novel degradable PIs were prepared from diamine 4,6-bis(4-aminophenoxy)pyrimidine with various commercially available aromatic dianhydrides by a conventional two-stage method. The resulting PIs could degrade fast under methylamine medium in N,N-dimethylacetamide, and the degradation mechanism was speculated by analyzing the degradation products. Compared with the traditional method, a facile and effective method for PI degradation was provided. The results suggested that incorporating 4,6-diphenoxypyrimidine structure into polymer chains may grow up to be a new method for polymer degradation. [ABSTRACT FROM PUBLISHER]

A novel heterocyclic diamine monomer based on pyrimidine ring, 2,4-bis(4-aminophenoxy)pyrimidine, was successfully synthesized. The obtained heterocyclic diamine was fully characterized and employed to synthesize a series of polyimides (PIs) by polycondensation with commercially available aromatic dianhydrides via the conventional two-step method. The effects of the pyrimidine rings into the main chain of the PIs were evaluated through the study of their solubility, thermal, mechanical, and optical properties. The inherent viscosities of the resulting poly(amic acid)s were in the range of 0.58–1.45 dL g−1. Meanwhile, the PIs had good thermal stability with the 5% weight loss temperatures of 445–475°C under nitrogen atmosphere as well as outstanding mechanical properties with tensile strength of 93–105 MPa and elongation at break of 3.6–4.2%. The cutoff wavelength of the PI films were in the range of 348–413 nm. [ABSTRACT FROM AUTHOR]

Pyridazine-containing aromatic diamine monomer, 3,6-bis(4-aminophenoxy)pyridazine (APPD), was successfully synthesized by a nucleophilic substitution reaction of 3,6-dichloropyridazine with para-aminophenol. The aromatic heterocyclic diamine was employed to synthesize a series of polyimides (PIs) by polycondensation with various commercially available aromatic dianhydrides in N,N-dimethylacetamide via the conventional two-step method and further thermal imidization forming polyimides. The inherent viscosities of the resulting poly (amic acid)s were in the range of 0.47–1.51 dL g−1. Meanwhile, strong and flexible PI films were obtained, which had good thermal resistance, with the glass transition temperatures of 214–305°C and the temperature at 5% weight loss of 421–463°C under nitrogen atmosphere, as well as outstanding mechanical properties with tensile strengths of 61–102 MPa and elongations at break of 2.8–64.7%. The cutoff wavelength of the PI films were ranged in 357–413 nm. [ABSTRACT FROM AUTHOR]

A diamine monomer, 4,4'-bis(5-amino-2-pyridinoxy)benzophenone, was designed and synthesized, and used to react with commercially different kinds of aromatic dianhydrides to prepare a series of polyimides containing pyridine and ketone units via the classical two-step procedure. Glass transition temperatures ( T g ) of the resultant polyimides PI-(1-5) derived from 4,4'-bis(5-amino-2-pyridinoxy) benzophenone with various dianhydrides ranged from 201 to 310 °C measured by differential scanning calorimetry. The temperatures for 5%wt loss of the resultant polyimides in nitrogen atmosphere obtained from the thermogravimetric analysis curves fell in the range of 472-501 °C. The temperatures for 10%wt loss of the resultant polyimides in nitrogen atmosphere fell in the range of 491-537 °C. Meanwhile, the char yields at 800 °C were in the range of 55.3-60.8%. Moreover, the moisture absorption of polyimide films was measured in the range of 0.37-2.09%. The thin films showed outstanding mechanical properties with tensile strengths of 103-145 MPa, an elongation at break of 12.9-15.2%, and a tensile modulus of 1.20-1.88 Gpa, respectively. The coefficients of thermal expansion of the resultant polyimides were obtained among 26-62 ppm °C -1 . To sum up, this series of polyimides had a good combination of properties applied for high-performance materials and showed promising potential applications in the fields of optoelectronic devices.