Synthesis and properties of organosoluble polyimides based on 4,4′‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzophenone

Abstract

A novel, fluorinated diamine monomer with the ether–ketone group, 4,4′‐bis(4‐amino‐2‐trifluoromethylphenoxy)benzophenone (2), was prepared through the nucleophilic substitution reaction of 2‐chloro‐5‐nitrobenzotrifluoride and 4,4′‐dihydroxybenzophenone in the presence of potassium carbonate, followed by catalytic reduction with hydrazine and Pd/C. Flourinated polyimides (PIs) 5a–f and copolyimides (co‐PIs) 5c/a–f were synthesized from 2 and various commercial aromatic dianhydrides via thermal or chemical imidization. PIs 5a–f had inherent viscosities ranging from 0.72 to 1.22 dL/g. Besides the chemical imidization of 5c(C), the 5(C) series were soluble in amide‐type solvents and even in less polar solvents, but PIs 5a–f prepared via thermal imidization were insoluble. PI films 5a–f exhibited tensile strengths ranging from 92 to 112 MPa, elongations at break from 8 to 15%, and initial moduli from 2.0 to 2.1 GPa. The glass‐transition temperatures of the 5 series were in the range of 232–278 °C, and the 10% weight‐loss temperatures were above 535 °C, with more than a 50% char yield at 800 °C in nitrogen. In comparison of the PI 5 series with the analogous non‐fluorinated PIs 6 series based on 4,4′‐bis(4‐aminophenoxy)benzophenone, the 5 series revealed better solubility, lower color intensity, dielectric constant, and moisture absorption. Their PI films had cutoff wavelengths between 370 and 410 nm, b* values ranging from 9.6 to 58.3, dielectric constants of 3.05–3.64 (1 MHz), with moisture absorption in the range of 0.08–0.38 wt %. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 222–236, 2004

High solubility and optical transparency of novel polyimides containing 3,3′,5,5′-tetramethyl pendant groups and 4-tert-butyltoluene moiety

“…In comparison with the analogous PI 4a and 4b non-containing 3,3 0 ,5,5 0 -tetramethyl groups, apparently, 3a and 3b showed better solubility. Meanwhile, they also showed an improved solubility compared with some fluorinated PEIs derived from the trifluoromethyl-substituted bis(ether amine)s and corresponding dianhydrides, especially in some low-boiling-point solvents [21][22][23]25,26]. It should be noted that good solubility in low-boiling-point solvents is critical for preparing PI films or coatings at a relatively low processing temperature, which is desirable for advanced microelectronics manufacturing applications.…”

“…However, some of these fluorinated PEIs derived from PMDA and BPDA still showed a limited solubility. For example, Yang studied a series of fluorinated PEIs derived from 4,4 0 -bis(4-amino-2-trifluoromethylphenoxy)-benzophenone, 1,4-bis(4-amino-2-trifluoromethylphenoxy)naphthalene and 2,5-bis(4-amino-2-trifluorome thylphenoxy)-tert-butylbenzene [22,25,26]. These materials derived from BPDA were almost insoluble in most common solvents.…”

“…These fluorinated PEIs are usually prepared derived from the trifluoromethyl-substituted bis(ether amine)s [21][22][23][24][25][26][27][28]. It was found that the incorporation of bulkily fluorinated groups into macromolecular backbones resulted in great benefits for improving polymer solubility as well as optical and dielectric performance, which attributed to the small dipole and the low polarizability of the C-F band as well as the increase in free volume.…”

“…Recently, considerable attention has been devoted to the fluorinated PIs, especially the trifluoromethyl-containing poly(ether imide)s (PEIs) [17][18][19][20][21][22][23][24][25][26][27][28]. These fluorinated PEIs are usually prepared derived from the trifluoromethyl-substituted bis(ether amine)s [21][22][23][24][25][26][27][28].…”

Synthesis and characterization of fluorinated polyimides derived from novel unsymmetrical diamines

“…As well known, introduction of geometrically or molecularly unsymmetrical diamine components into the polyimide main chain has led to new polyimides with improved solubility, melt processability and other desirable properties [14][15][16][17][18][19]; additionally, fluorination is also known for increasing intermolecule space while enhancing the solubility, optical transparency and lower moisture absorption of polyimides [6,20,21].…”