Novel organosoluable aromatic polyimides derived from unsymmetrical 1,3-bis(4-aminophenoxy)naphthalene and aromatic dianhydrides

Abstract

A novel unsymmetrical diamine, 1,3-bis(4-aminophenoxy)naphthalene, was prepared through the nucleophilic displacement of 1,3-dihydroxynaphthalene with p-fluoronitrobenzene in the presence of potassium carbonate, followed by catalytic reduction with hydrazine. A series of novel aromatic polyimides containing bis(phenoxy)naphthalene units were synthesized from the unsymmetrical diamine and a range of aromatic tetracarboxylic dianhydrides via the usual two-step procedures that included ring-opening polyaddition and thermal/ chemical cyclodehydration. The poly(amic acid)s had inherent viscosities ranging from 0.65 to 2.01 dL/g. All the poly(amic acid)s could be converted thermally into transparent, flexible, and tough polyimide films. Most of the polyimides were soluble in organic solvents, such as dimethylacetamide, N-methyl-2-pyrrolidone, m-cresol, or ochlorophenol due to the unsymmetrical and bulky pendant naphthalene groups. The tensile strength and elongation at break of the polyimide films ranged from 74 to 97 MPa and 4 to 7%, respectively. These polyimides had glass transition temperatures ranging from 221 to 312 ºC. Thermogravimetric analysis revealed these polymers to be fairly stable up to 500 ºC, and the 10% weight loss temperature were recorded in the range of 531-580 ºC in nitrogen and 522-570 ºC in air. The substituted position effect of bis(phenoxy)naphthalene on the properties of the polyimides were investigated. The polyimides derived from unsymmetrical 1,3-substituted bis(4-aminophenoxy)naphthalene showed better solubility without sacrificing their thermal and mechanical properties due to the unsymmetrical and bulky pendant effects.

Synthesis and characterization of unsymmetrical benzonitrile‐containing polyimides: Viscosity‐lowering effect and dielectric properties

“…Aromatic poly(ether‐imides) derived from an unsymmetrical indane‐based diamine have been evaluated for gas permeation properties . Unsymmetrical diamines containing thiazole ring, triaryl imidazole pendant group, diphenylpyridyl pendant group, naphthalene unit, and phthalazinone moiety, have been designed for the syntheses of their respective PIs. In other cases, the PIs derived from unsymmetrical dianhydrides have also been prepared for the similar reasons .…”

Novel low‐dielectric constant and soluble polyimides from diamines containing fluorene and pyridine unit

“…Consequently, it is supremely urgent to develop dissolvable and processable PI's with high transparency and low-dielectric constant. 5,6 Various methods have been tried to overcome these drawbacks without compromising the mechanical and thermal properties of PI's, [7][8][9] including the incorporation of flexible linkages, 10,11 unsymmetrical or noncoplanar structures, 12,13 fluorinated structures, 14,15 and bulky pendant substituents 16,17 to the polymer chains.…”

Research and Manufacture of Thermoplastic Polyimide Engineering Plastics

“…Aromatic polyimides are very attractive for their high mechanical strength, outstanding thermal stability and are widely used as plastics for a variety of applications such as automobile and aircraft parts, electronic packaging, films, adhesives, and matrix materials for composites [1,2]. Their limited solubility in organic solvents and their high glass transition temperatures make aromatic polyimides difficult to fabricate and thermoplastic.…”