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Electromagnetic shielding performance has been achieved for a polyimide (PI)-matrix composite by the strategy of self-metallization of its thermosetting PI matrix. Self-metallization of the thermosetting PI was realized by silver ion/poly(amic acid) (PAA) precursor ion exchange and thermal reduction. The factors influencing the self-metallization were investigated. The electrical conductivity and integrity for the surface of the PI were achieved by optimization of ion exchange/thermal reduction parameters. The fabricated PI-matrix composite exhibits a maximum electromagnetic interference shielding effectiveness value of 81 dB. Importantly, the electromagnetic shielding performance can be maintained even after heat condition of 300°C. Meanwhile, the surface-metallized PI composite exhibits mechanical property equivalent to the pristine composite, and an Ag/matrix interfacial strength higher than 19.6 MPa. Besides, self-metallization mechanism of the thermosetting PI was investigated.

Intrinsically heat-sealable polyimides with atomic oxygen (AO) resistance (ARPIs) were synthesized from 2,3,3′,4′-oxydiphthalic anhydride (aODPA), 2,5-bis[(4-aminophenoxy)phenyl]diphenylphosphine oxide (BADPO), and para-phenylenediamine (PDA). The effects of the molecular structure and diamine ratio were investigated on the properties of the ARPI, including mechanical property, thermal property, heat sealability, and AO resistance. Heat sealability and AO resistance were realized for the ARPI film by combining the asymmetry of the aODPA moiety and the passivated layer forming characteristic of diphenylphosphine phosphine oxide group. Meanwhile, the deficiency of low mechanical strength and thermal resistance, commonly existing in a completely BADPO-derived polyimide system, was remedied effectively by the higher reactivity and rigidity of PDA.

A series of polyimides (PIs) with good heat sealability were synthesized from an asymmetric aromatic dianhydride, 2,3,3′,4′-oxydiphthalic anhydride, and aromatic ether diamines with different structures featured by ether amounts, substituted positions of ether linkages, and substituted positions of amino groups. In detail, the effects of these three substructures in the diamine were investigated on thermal resistance, thermoplasticity, and heat sealability of the PI film. It is found that the glass transition temperatures and heat-sealing strengths of the prepared PI films are influenced to different extents by the variations of the substructures, because of their different contributions to the chain mobility. These PI films are demonstrated to possess good heat sealability evidenced by completely fused heat-sealing interfaces and high heat-sealing strengths up to 580 N m−1.

Recent research and development of colorless and optically transparent polyimide (CPI) films have been reviewed. CPI films possess both of the merits of conventional aromatic PI films and common polymer optical film; thus have been widely investigated as components for microelectronic and optoelectronic fabrications. The current review coveres the latest research and development for CPI films, including synthesis chemistry, manufacturing process, and engineering applications. Especially, this review focuses on the applications of CPI films as flexible substrates for optoelectrical devices, such as flexible active matrix organic light emitting display devices (AMOLEDs), flexible printing circuit boards (FPCBs), and flexible solar cells. (C) 2015 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Novel ether-bridged fluorinated poly(phenylquinoxaline) (PEPPQ) dielectric films with enhanced glass-transition temperatures (Tg) have been developed in order to meet the high-temperature demands f...

Two fluorinated polyphenylquinoxalines (FPPQs) have been prepared from the newly developed trifluoromethyl-containing aromatic bis(alpha-diketone) monomers (FTKs) and aromatic bis(o-diamine). The thermal, electrical, and hydrolytic properties of the FPPQs were investigated. The results reveal that the developed FPPQ films exhibit low dielectric constants of 2.78-2.85, which are closely related to their excellent hydrophobic nature. The FPPQ films also manifest excellent hydrolytic stability in the aqueous environment. Meanwhile, the intrinsically high thermal stability and electrical resistivity are maintained for the FPPQs.

A series of polyimide aerogels with intrinsically atomic-oxygen-resistant features have been synthesized. For this purpose, 3,3',4,4'-biphenyltetracarboxylic dianhydride (s-BPDA) was copolymerized with 2,2'-dimethylbenzidine (DMBZ) and a polyhedral oligomeric silsesquioxane (POSS)-containing aromatic diamine, N-[(heptaisobutylPOSS)propyl]-3,5-diaminobenzamide (DA-POSS), with octa(aminophenyl)silsesquioxane (OAPS) as the crosslinker via sol-gel procedures followed by supercritical carbon dioxide (scCO(2)) drying treatments.

Semi-alicyclic polyimides (PI-1–PI-4) have been prepared from a newly-developed alicyclic dianhydride, 3,4-dicarboxy-1,2,3,4-tetrahydro-6- tert -butyl-1-naphthalene succinic dianhydride (TTDA) and various aromatic diamines. The asymmetrical alicyclic tetralin structure in TTDA endowed the derived PI resins good solubility in various organic solvents. They were soluble not only in polar aprotic solvents but also in solvents with low boiling points including dichloromethane and tetrahydrofuran. Flexible and tough PI films were successfully cast from their N -methyl-2-pyrrolidone (NMP) solution except PI-1 derived from TTDA and 4,4′-oxydianiline (ODA). The PI films exhibited good optical transparency in the ultraviolet and visible light region with optical transmittances around 80% at a wavelength of 400 nm. The PI films showed good thermal stability up to 400 °C in nitrogen, after that they thermally decomposed rapidly. The thermal degradation behaviors of the PIs were investigated by means of thermogravimetric analysis-mass spectrometry (TG-MS), thermogravimetric analysis-Fourier transform infrared spectrometry (TG-FTIR) and the real time FTIR spectra (RT-FTIR) analysis techniques. The results revealed that the decomposition of PI-1 (as a representative) took place mainly in the range of 450–550 °C. The major degradative fragments at 500 °C were clearly identified as the tert -butyl-substituted tetralin moiety and its dealkylation products. Therefore, it can be deduced that for the TTDA-PIs, the single bond bridge attached the maleic anhydride and tetralin anhydride units in TTDA moiety might break first during the heating; thus producing the tetralin fragments.

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 degrees C. (c) 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43058.