Intrinsically Black Polyimide with Retained Insulation and Thermal Properties: A Black Anthraquinone Derivative Capable of Linear Copolymerization

Abstract

Black polyimide (BPI) is increasingly in demand for the development of photoelectric devices in place of yellow transparent polyimide, but BPI doped with carbon black shows serious insulation and mechanical performance deficiencies due to pinholes and uneven dispersion. Intrinsically BPI has thus attracted increasing interest in science and industry. Anthraquinone derivatives have an ample high molar extinction coefficient (ε), and appending as many auxochromes (−OH and −NH2) as possible on the anthraquinone skeleton can extend its light absorption range, thereby achieving complete UV–visible light absorption. However, the greatest obstacle to its application in BPI is retaining the monomer bifunctionality to avoid gel formation. In this work, a linearly polymerizable anthraquinone derivative, 2,4,5,7-tetraamino-1,8-dihydroxyanthracene-9,10-dione (4NADA), has been developed. Structural analysis of this monomer bearing multiple active groups by 1H NMR, Fourier-transform infrared, and theoretical calculations has demonstrated that the auxochrome groups show different nucleophilic activities owing to the formation of intramolecular hydrogen bonds, such that only p-amino groups (2- and 7-positions) can participate in the polymerization reaction. Subsequently, 4NADA was copolymerized into a Kapton-type polyimide. We found that low-level introduction of 4NADA (4%) afforded a spectrally BPI film that maintained the electrical insulation and heat resistance properties of polyimide. This method, equivalent to embedding a black monomer in polyimide chains, has merits of economy, universality, process consistency, ready accessibility, and superior performance.

Colorless Polyimides from Fluorinated Ladder Diamines Containing Norbornyl Benzocyclobutene Segments

“…Fluorinated N2BC-containing CPIs exhibited good thermal stability compared to the semialicyclic polyimides reported previously, − which was reflected by their 5% weight loss temperature ( T 5% ) ranging from 437 to 468 °C under nitrogen (Figure S7 and Table ). However, their T 5% values were apparently less than those of conventional aromatic polyimides. ,,,, This result could be attributed to the alicyclic segments in these CPIs, which were more susceptible to thermal degradation compared to aromatic moieties. For the given dianhydrides, CANAL-2F-derived CPIs exhibited higher T 5% values than those from CANAL-CF 3 and CANAL-F/CF 3 .…”

“…However, their T 5% values were apparently less than those of conventional aromatic polyimides. 14,24,26,40,41 This result could be attributed to the alicyclic segments in these CPIs, which were more susceptible to thermal degradation compared to aromatic moieties. For the given dianhydrides, CANAL-2F-derived CPIs exhibited higher T 5% values than those from CANAL-CF 3 and CANAL-F/CF 3 .…”

“…The mechanical properties of these CPIs were apparently inferior to those of wholly aromatic polyimides (such as ODA-PMDA, PDA-BPDA, and TFMB-BPDA) due to their reduced inter-and intramolecular interactions. 26,40,49 For a given dianhydride, CANAL-2F-derived CPIs exhibited the best mechanical properties due to their most compact chain packing and additional dipole−dipole interactions. For certain diamines, CpODA-derived CPIs exhibited the highest elongation-atbreak values due to their sub-T g relaxation at around room temperature.…”

Enhanced thermal conductivity in copolymerized polyimide

“…4NADA was synthesized from 1,8-dihydroxyanthracene-9,10-dione via nitrification and subsequent reduction, following the route mentioned in our previous work. 21 The obtained diamine monomer was copolymerized with 4,4′-diaminodiphenyl ether (ODA) and 1,2,4,5-benzenetetracarboxylic dianhydride to afford a viscous polyamic acid (PAA) solution. After vacuum defoaming, the PAA solution was coated onto a glass substrate and subsequently cured by a thermal annealing process to obtain corresponding PI films.…”

Progress in Aromatic Polyimide Films for Electronic Applications: Preparation, Structure and Properties

“…Aromatic polyimide films have been widely used in many high-tech fields, including electrical insulation [ 15 , 16 , 17 , 18 , 19 , 20 ], electronic packaging [ 21 , 22 ], and aerospace [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ], due to their excellent combination of thermal, mechanical, and electrical properties. Aromatic polyimide films can be made by casting the polyimide precursor solution–polyamic acid (PAA) on the substrate surface, and then thermally baking it to form a self-supporting gelled film.…”