Highly transparent and organosoluble polyimides derived from 2,2′‐disubstituted‐4,4′‐oxydianilines

Abstract

To improve the optical transparency and organosolubility of aromatic polyimides derived from 4,4 0 -oxydianiline (4,4 0 -ODA), two new aromatic diamines, 2,2 0 -diiodo-4,4 0 -oxydianiline (DI-ODA) and 2,2 0 -bis0 -oxydianiline (BTFP-ODA) were synthesized by using 4,4 0 -ODA as a starting material. Novel polyimides were prepared from these two diamines with various commercially available aromatic dianhydrides via a one-step high-temperature polycondensation procedure. Most of these polyimides showed enhanced solubility in common organic solvents compared with those corresponding polyimides derived from 4,4 0 -ODA. Especially, polyimide derived from BTFP-ODA and rigid pyromellitic dianhydride (PMDA) was also soluble in DMF, DMAc, DMSO, NMP, and m-cresol at room temperature. These polyimides had inherent viscosities from 0.41 to 1.26 dLg À1 in NMP or m-cresol at 30 C. Transparent, flexible, and tough films can be obtained by casting from their DMAc or m-cresol solutions. These films had the UV onset wavelengths in the range of 347-391 nm and the wavelengths at 80% transmission of 445-544 nm, indicating high optical transparency. They also exhibited good thermal stability with glass transition temperatures in the range of 260-327 C. The decomposition temperatures of these polyimides at 5% weight loss under nitrogen were 429-609 C. Because of the weak carbon-iodine bond, polyimides derived from DI-ODA decomposed at lower temperatures than polyimides derived from BTFP-ODA. The effects of the substituents at the 2 and 2 0 positions of 4,4 0 -ODA on the properties of polyimides are also discussed. High optical transparency and good solubility combined with high thermal stability make these polyimides potential candidates for soft electronics applications.

Organosoluble polyimides derived from asymmetric 2‐substituted‐and 2,2′,6‐trisubstituted‐4,4′‐oxydianilines

“…For example, T 5% of PI10b , PI11b , PI12b and PI13b are 511, 492, 572 and 576 °C, respectively. This is possibly a result of the lower carbon–bromine bond energy …”

“…In our previous study, 4,4′‐ODA‐based diamines with trifluoromethyl‐substituted phenyl or bromide at 2,2′‐ or 2,2′,6‐ and 6′‐positions were reported . Polyimides derived from these diamines all showed enhanced solubility over that of 4,4′‐ODA‐based polyimides.…”

“…In our previous study, 4,4 -ODA-based diamines with trifluoromethyl-substituted phenyl or bromide at 2,2 -or 2,2 ,6-and 6 -positions were reported. 25,26 Polyimides derived from these diamines all showed enhanced solubility over that of 4,4 -ODAbased polyimides. These diamines were synthesized directly from 4,4 -ODA, which was first oxidized, then brominated and finally reduced.…”

Structure, thermal stability, electrochemical behaviors, and mechanical properties of organosoluble polyimide with pyrimidine ring in the main chain

“…However, PI with the wholly aromatic structure has poor solubility and non‐melting property attributed to its rigid main chain and strong inter‐chain interaction, which limit its practical applications seriously. Fortunately, researchers have mainly concluded four aspects of structure modification by enhancing the flexibility of molecular main chain and weakening the intermolecular interaction of PI in order to improve its solubility in the past decades, which involved the incorporation of thermally stable but flexible linkages in the main chain, the synthesis of unsymmetrical linkages in the main chain, the introduction of polar or nonpolar substituent branched to the main chain, and the destruction of symmetrical structure of the main chain with the introduction of hyperbranched structure . In particular, the researchers have found that the incorporation of aromatic heterocyclic compounds into the main chain could form thermally stable and flexible linkages in PIs main chain, which would reduce the intermolecular interaction effectively and improve the solubility remarkably .…”

Synthesis of Polycyclic Amines through Mild Metal‐Free Tandem Cross‐Dehydrogenative Coupling/Intramolecular Hydroarylation of N‐Aryltetrahydroisoquinolines and Crotonaldehyde

“…Symmetrical diaryl ether polymers are very important and increasingly interesting on account of their application in the aerospace and microelectronics industries, principally in the form of films or moldings. This is attributable to their excellent thermal stability, electric properties, and chemical resistance 9. Many synthetic methods thus far reported have shown that symmetrical diaryl ethers are important building blocks for large varieties of natural and artificial products (Scheme ).…”