Synthesis and characterization of organosoluble, transparent, and hydrophobic fluorinated polyimides derived from 3,3′-diisopropyl-4,4′-diaminodiphenyl-4′′-trifluoromethyltoluene

Abstract

A novel aromatic fluorinated diamine monomer, 3,3′-diisopropyl-4,4′-diaminodiphenyl-4′′-trifluoromethyltoluene, was synthesized by coupling of 2-isopropylaniline and 4-(trifluoromethyl)benzaldehyde and its structure was confirmed by Fourier transform infrared spectroscopy, nuclear magnetic resonance, elemental analysis, and mass spectrometry, and then used to prepare a series of fluorinated polyimides (FPIs) by polycondensation reaction with various commercial dianhydrides via conventional one-step method. The obtained FPIs present excellent solubility in most organic solvents and enough to cast into tough and flexible films. All the FPI films show good optical transparency and light color with the cutoff wavelengths in range of 307–362 nm and the average transmittance above 86%. These polymer films also exhibit high glass transition temperature in range of 261–331°C and thermal stability with 10% weigh loss above 463°C under nitrogen atmosphere. Furthermore, they exhibit outstanding mechanical properties with tensile strengths of 65.9–94.3 MPa, elongation at break of 11.4–13.8%, Young’s modulus of 1.6–1.9 GPa, and low dielectric constants in range of 2.75–3.10 at 1 MHz as well as prominent hydrophobicity with the contact angle in the range of 87.3–93.9°.

Synthesis and Characterization of Organosoluble, Thermal Stable and Hydrophobic Polyimides Derived from 4-(4-(1-pyrrolidinyl)phenyl)-2,6-bis(4-(4-aminophenoxy)phenyl)pyridine

“…For example, poor solubility in most organic solvents, high softening and meting temperatures, and deeply color that often limit their widespread application in various advanced technologies [13,14,15,16,17,18,19]. Thus, many efforts have been devoted to improving the solubility, processability, and highly optical transparent of PIs by the incorporation of flexible or twist linkages [20,21,22,23], asymmetric noncoplanar units [24,25,26], bulky pendant groups [27,28,29], and fluorinated substituents [30,31,32,33,34] into the polymer backbones.…”

Recent Trends on Transparent Colorless Polyimides with Balanced Thermal and Optical Properties: Design and Synthesis

“…An aromatic fluorinated diamine monomer, 3,3 ′ ‐diisopropyl‐4,4 ′ ‐diaminodiphenyl‐4 ′′ ‐trifluoromethyltoluene (PAPFT), was synthesized by coupling of 2‐isopropylaniline and 4‐(trifluoromethyl)benzaldehyde by Liu et al. ( Scheme ) . The PAPFT based PI films presented excellent solubility, good optical transparency (λ 0 in the range of 307–362 nm and the average transmittance above 86%), and high glass transition temperature in the range of 261–331 °C.…”

Organosoluble and transparent cardo polyimides with high Tg derived from 9,9-bis(4-aminophenyl)xanthene

“…For instance, a decrease in rigidity lowered the heat resistance while increasing the solubility. In addition, the introduction of fluorine substituents like trifluoromethyl groups into the backbone or side chain of PIs [13][14][15] resulted in an enhanced solubility and optical transparency, together with a lower dielectric constant, but most of the fluorinated monomers are expensive, noncommercial available, and their preparation usually requires a multistep synthetic procedure. Nevertheless, another effective approach is to incorporate bulky pendent loops (usually named as cardo groups) along the PI backbone, which cannot only inhibit the close packing of polymer chains to improve their solubility without sacrificing the thermal stability but also reduce the formation of intermolecular charge-transfer complex to form transparent and colorless films.…”