A series of inherently heat-sealable copolyimides (CPIs) with high glass transition temperatures were synthesized from 2,3,3′,4′-oxydiphthalic anhydride (aODPA) and bicomponent diamines, 4,4′-oxydianiline (ODA) and para-phenylenediamine (PDA). The PI chain rigidity was manipulated by the regulation of the diamine ratio, and its effects on the heat sealability and thermal resistance of the derived CPI films were investigated in detail. The results show that these films are in possession of both good heat sealability and thermal resistance due to the synergetic effect of the asymmetry of aODPA and the rigidity of PDA. It is also found that there exists one critical PDA content that distinguishes the heat-sealing behaviors of the CPI films, and the relevant mechanism was established. Especially for CPI-5, the heat-sealing strength is up to 350 N m⁻¹ simultaneously with a relatively high T_g of 310°C. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43058.

A novel phosphorous-silicone-nitrogen ternary flame retardant (FR), [(1,1,3,3-tetramethyl-1,3-disilazanediyl)di-2,1-ethanediyl]bis(diphenylphosphine oxide) (PSiN) was synthesized with high yield via a one-step procedure by the reaction of diphenylphosphine oxide and vinyl-terminated silazane with triethylborane as the catalyst. The chemical structure of the target compound was confirmed by nuclear magnetic resonances, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and Flourier transform infrared measurements. The developed PSiN FR was applied in the flame retardancy of o-cresol novolac epoxy (CNE)/phenolic novolac (PN) hardener system. Effects of PSiN on the processability, thermal properties, especially the flame retardancy properties of the composites were investigated. Experimental results revealed that addition of PSiN improved the flowability of the CNE/PN systems, while the thermal stability of the epoxy thermosets was maintained. Meanwhile, the incorporation of PSiN was in favor of the formation of char during the thermal degradation process of the epoxy thermosets. The limited oxygen index of the epoxy system increased along with the PSiN content. An UL 94 V-0 FR rating was achieved when the weight content of PSiN in the epoxy composites reached 20 wt %. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40412.

A novel aromatic diamine, 1,1-bis(4-amino-3,5-dimethylphenyl)-1-(3,4,5-trifluorophenyl)-2,2,2-trifluoroethane, containing a pendant polyfluorinated phenyl group, a trifluoromethyl group, and methyl groups ortho-substituted to the amino groups in the structure was synthesized and characterized. The diamine was polymerized with several aromatic dianhydrides, including 3,3′,4,4′-biphenyltetracarboxylic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride, 4,4′-oxydiphthalic anhydride, and 4,4′-hexafluoroisopropylidene diphthalic anhydride, via a high-temperature one-step procedure to afford four polyimides (PIs) with inherent viscosities of 0.47–0.70 dL/g. The PIs exhibited excellent solubilities in a variety of organic solvents. They were soluble not only in polar aprotic solvents but in many common solvents, such as cyclopentanone, tetrahydrofuran, and even toluene at room temperature. The tough and flexible PI films cast from the PI solutions exhibited good thermal stabilities and acceptable tensile properties. The glass-transition temperatures were in the range 312–365°C, and the 5% weight loss temperatures were all higher than 480°C in nitrogen. The films had tensile strengths in the range 76–99 MPa, tensile moduli of 2.2–2.8 GPa, and elongations at break of 5–8%. In addition, the PI films exhibited excellent transparency in the visible light region with cutoff wavelength as low as 302 nm and transmittance higher than 88% at the wavelength of 450 nm. The PI films showed low dielectric constants ranging from 2.50–2.68 and low moisture absorptions of less than 0.56%. The good combined properties of the PIs mainly resulted from the synergic effects of the different substituents. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009