Transparent and organosoluble cardo polyimides with different trans/cis ratios of 1,4‐diaminocyclohexane via aromatic nucleophilic substitution polymerization

Abstract

Two series of cardo polyimides were prepared from 1,4‐bis(4‐fluorophthalimide)cyclohexane with different trans/cis ratios and phenolphthalein/o‐cresolphthalein via aromatic nucleophilic substitution reaction. The inherent viscosities of the synthesized polymers were found to be 0.55–0.66 dL g−1 in N,N′‐dimethylacetamide. The cardo polyimides showed excellent solubility in organic solvents, high glass transition temperatures (Tg) of 275–312 °C and moderate thermal stability with 5% weight loss temperatures (Td5%) of 415–441 °C in nitrogen and 370–436 °C in air. The polyimide films exhibited high optical transparency with cut‐off wavelengths of 350–355 nm and moderate mechanical properties. The different properties of the polymers caused by trans and cis configurations of 1,4‐diaminocyclohexane were also investigated. It was found that with an increasing content of trans configuration of 1,4‐diaminocyclohexane in the polyimide backbone, Tg of the polyimides increased as well as Td5%, while the solubility gradually decreased. The polyimide films had good optical transparency regardless of trans/cis configuration. © 2018 Society of Chemical Industry

Reductive Amination of Ketonic Compounds Catalyzed by Cp*Ir(III) Complexes Bearing a Picolinamidato Ligand

“…The diastereoselective formation of 4-substituted cyclohexylamines was also achieved by using 2c for the DRA of 4-(tertbutyl)cyclohexan-1-one (4ac) and 4-phenylcyclohexan-1-one (4ad), leading to excellent cis/trans ratios of 99/1 and 93/7 (for entries 2 and 3, respectively). The application of the competent Ir catalyst was extended to the double amination of cyclohexane-1,4-dione (4ae), which was transformed into a potential monomer for poly(imide) synthesis, 16 cis-cyclohexane-1,4-diamine (5ae), in 65% yield with a diastereomeric ratio of 98/2, after the reaction was conducted on a subkilogram scale in water using 8 equiv of ammonium formate (entry 4). The relative cis-configuration of the major product was confirmed by single-crystal X-ray analysis of a bisacetamide derivative 5af, obtained by diacetylation of 5ae (see the Experimental Section).…”

Soluble copolyimides containing 4,4′-isopropylidenedicyclohexanol (HBPA) isomer units: Synthesis, characterization, thermal, mechanical, and optical properties

“…The high transmittances of the copolyimides could be ascribed to two aspects: firstly, the nonplanar alicyclic diamine residues owned low electron-donating ability, thereby decreasing both intra- and intermolecular CT interactions and secondly, the bulky and weakly polarizable trifluoromethyl hampered close packing of molecular chains, which inhibited the CT interactions effectively. 10,13,29,30 In addition, no significant rules on the optical properties of the copolyimides were found with the decreased content of H″BPDA, which could be attributed to the fact that the incorporation of alicyclic diamines and the bulky and weakly polarizable trifluoromethyl presented “already weakened CT interactions,” the difference of axial C–O and equatorial C–O in the improvement of the polyimide film transmittance could not be reflected.…”

Recent development of polyimides: Synthesis, processing, and application in gas separation

“…The ANS monomers with bulky side group are more accessible than diamine or dianhydride counterparts. Therefore, in the last two decades, ANS polymerization has been mainly used for preparing organo-soluble lightcolored (Figure 6B) [64][65][66][67][68][69][70][71][72] and colorless PIs (Figure 6C). 65,66,68,71 Ether and isopropyl linkages as well as bulky side groups (e.g., cardo unit) are common for improving solubility in organic solvents and reduce colors.…”

“…(C) examples of organosoluble, colorless PIs, most of which are prepared via NAS. All the examples contain cardo groups, which endow their useful properties (C1–C5) 66,68,71 …”