Synthesis and characterization of soluble polyimides containing trifluoromethyl groups in their backbone

Abstract

A series of polyimides were synthesized from 2,2‐Bis(3,4‐dicarboxyphenyl)hexafluoropropane, 2,2‐bis(3‐amino‐4‐hydroxyphenyl)‐hexafluoropropane, and 4,4′‐oxydianiline by chemical imidization. The effects of the diamine ratios on the properties of the films were evaluated through the study of their thermal, electrical, and morphological properties. All the polymers exhibited better solubility in most of the organic solvents and hence were easily processable. Polyimides with more 2,2‐bis(3‐amino‐4‐hydroxyphenyl)‐hexafluoropropane exhibited better solubility and a low refractive index, which is highly desired for microelectronic applications. The dielectric constant and birefringence were strongly dependent on the fluorine content. With an increase in the fluorine substitution, both the dielectric constant and birefringence decreased. All the polymers exhibited high thermal stability (>400 °C). The absence of crystalline melting in differential scanning calorimetry and broad wide‐angle X‐ray diffraction patterns revealed the amorphous nature of the polymers, which was due to the presence of bulky CF3 groups and hinged ether linkages of the diamine component. The residual stress values decreased with an increase in the 4,4′‐oxydianiline content, and the results were in agreement with the dielectric constant. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4303–4312, 2004

The effect of crosslinked networks with poly(ethylene glycol) on sulfonated polyimide for polymer electrolyte membrane fuel cell

“…This is attributed to the decomposition of PEG group, and it decomposes along with the sulfonic acid group, accounting for the decreased second‐step degradation temperature. The third step indicates the decomposition of the polyimide backbone 31. Although it was expected that crosslinking will improve the thermal stability, the third step showed almost similar degradation temperature.…”

“…Then, this sulfonated polyimide powder terminated with HFBAPP was added to a conical flask with 25 mL of NMP and 0.4 mmol of MA and then, the solution was stirred at room temperature for 12 h. For the chemical imidization, 2 mmol of pyridine and 2 mmol of acetic anhydride mixture was added to this solution and then reacted at 115 °C for 10 h. After the reaction, the mixture was cooled to room temperature and the solution was poured into methyl alcohol. The fiber‐like precipitate was filtered off, washed, with acetone thoroughly and dried under vacuum at 80 °C for 15 h 31…”

Preparation of poly(amic acid) and polyimide derived from 3,3′,4,4′‐benzophenonetetracarboxylic dianhydride with different diamines by microwave irradiation

“…The d ‐spacing value was calculated with Bragg's equation by reported methods 37, 38. As first shown by Bragg et al, the Bragg equation can be expressed as follows: where X‐ray wavelength λ is 0.154 nm, θ is the Bragg angle (°), and d is the d ‐spacing of the polymer.…”

Preparation and characterization of quartz‐fiber‐cloth‐reinforced, polymerization‐of‐monomer‐reactant‐type polyimide substrates with a high impact strength

“…Hasegawa also found that PI derived from 1,2,3,4‐cyclobutanetetracarboxylic dianhydride and TFDB had a lower dielectric constant (2.66), and the dielectric constant of PI derived from trans −1,4‐cyclohexanediamine and 3,3′,4,4′‐biphenyltetracarboxylic dianhydride was 2.85, although the value was estimated by the average refractive index. A lot of work has also been done on fluorinate materials, but most of these works have concentrated on the film properties, and few of them have been applied to rigid‐substrate packaging materials.…”