Novel thermal stable organosoluble polyamides and polyimides based on quinoxalin bulky pendent group

Abstract

A new diamine containing a bulky diphenylquinoxalin pendant, 3,5-diamino-N-(2,3-diphenylquinoxalin-7-yl)benzamide (DQB), was synthesized in four steps through the nucleophilic aromatic substitution of 3,5-dinitrobenzoylchloride with 2,3-diphenylquinoxalin-6-amine and subsequent catalytic reduction. All intermediates and DQB were fully characterized by FTIR, NMR and elemental analysis. A series of polyamides PA(a-e) was synthesized from this diamine by direct polycondensation with various dicarboxylic acids, triphenyl phosphate and pyridine in N-methyl-2-pyrrolidynone (NMP). Three polyimides PI(a-c) were synthesized from this diamine using commercial dianhydrides in two-step polycondensation. Characterization of polymers was accomplished by FTIR, H NMR, elemental analysis, DSC, DMTA, GPC, and TGA. The intrinsic viscosities of PAs ranged from 0.54 to 0.67 dL/g. PAs displayed T g values of 140-298 o C and 10% weight loss of 415-485 o C in N 2 . The T g values of the PIs varied between 200 and 310 o C, with 10% weight loss above 500 o C in N 2 . The PAs were soluble in common polar aprotic solvents at room temperature whereas the aromatic PIs were dissolved by heating at 60 o C.

Synthesis and characterization of novel aromatic polyamides bearing CF3, quinoxaline‐anthraquinone pendants: Study of photophysical and electrochemical properties by using nanocomposite electrode paste

“…Hydrolysis of 4,4′‐dimethoxy benzyl in aqueous solution of HBr and glacial acetic acid was applied for the synthesis of 4,4′‐dihydroxy benzyl. Addition reaction between an aromatic ortho‐diamine and carbonyl groups of benzyl is a well known procedure for the preparation of quinoxaline system 29, 30. Thus 1,2‐diaminoanthraquinone and 4,4′‐dihydroxy benzyl in an addition reaction in acetic acid gave a bisphenol bearing aromatic functional of quinoxaline‐anthraquinone in its structure, 2,3‐bis(4‐hydroxyphenyl)naphtho[2,3‐f]quinoxaline‐7,12‐dione (BNQ).…”

Soluble N‐substituted poly(benzimidazole imide)s via C−N coupling reaction

“…However, because of the poor solubility of PIs, their application scope is limited . Much research effort has been dedicated to the structural modification of PIs to improve their solubility in normal organic solvents . In particular, introducing benzimidazole rings to the PI molecular backbone can clearly enhance the solubility while maintaining thermal and mechanical properties.…”

Synthesis and characterization of branched phenylethynyl-terminated polyimides

“…The main methods include insertion of flexible linkage on the main chain [12,13], utilization of noncoplanar or asymmetric monomers [5,[14][15][16], the incorporation of bulky pendant groups into the polymer backbones [17,18], etc. However, the monomers mentioned above are often scarce, expensive, and difficult to achieve industrial production.…”