Soluble and transparent polyimides from unsymmetrical diamine containing two trifluoromethyl groups

Abstract

A new unsymmetrical diamine monomer containing two trifluoromethyl (CF 3 ) groups is prepared from 2-bromo-5nitro-1,3-bis(trifluoromethyl)benzene. The monomer is polymerized with typical dianhydrides, in this case PMDA, BPDA, BTDA, ODPA, and 6-FDA, using a one-pot synthetic method to obtain corresponding polyimides. All of the prepared polyimides are readily soluble in many organic solvents and can be solution-cast into transparent, flexible, and tough films. These films have a UV-vis absorption cut-off wavelength at 340-375 nm and light transparencies of 87-91% at a wavelength of 550 nm. Incorporation of two CF 3 groups unsymmetrically into rigid polyimides improves their solubility and transparencies without decreasing their physical properties. The polymers V C 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4413-4422

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

“…Kim et al. designed and synthesized an unsymmetrical –CF 3 substituted diamine monomer, 4‐(4 ′ ‐aminophenoxy)‐3,5‐bis(trifluoromethyl)aniline (3), following a two‐step methodology, as shown in Scheme . Nucleophilic aromatic substitution reaction (SNAr) of 2‐bromo‐5‐nitro‐1,3 bis(trifluoromethyl)benzene (1) with 4‐nitrophenol in the presence of K 2 CO 3 produced the dinitro compound (2) which on subsequent reduction by H 2 in the presence of Pd/C catalyst delivered the desired diamine 3.…”

“…Synthesis of the unsymmetrical diamine monomer. Reproduced with permission . Copyright 2013, John Wiley & Sons, Inc.…”

Thermal Cycloimidization Study of Polyimides and Poly(amide imide)s Synthesized from Low-Temperature Solution Polymerization

“…Most of these approaches to obtain soluble polymers were aimed at reduction of several types of chain-chain interactions, such as chain packing (e.g., crystallinity), charge transfer, and electronic polarization interaction. Polyimides, containing structurally asymmetric diamine monomers that contain flexible ether linkages [17] or bulky trifluoromethyl [18,19] substituent groups showed enhanced solubility behavior. Our research group has also previously reported the preparation of fluorinated PAIs [20] and poly(amide-imide)s-poly(amide imide) composite membranes by interfacial polymerization technique.…”

Synthesis and characterization of highly-fluorinated colorless polyimides derived from 4,4′-((perfluoro-[1,1′-biphenyl]-4,4′-diyl)bis(oxy))bis(2,6-dimethylaniline) and aromatic dianhydrides

“…To overcome these problems of PIs, many effort has been focused on synthesis of Low-k and colorless PIs, without deterioration of the resulting PIs [16e20]. There are several approaches to prepare colorless PIs, including the introduction of flexible and unsymmetrical linkages or noncoplanar monomers and bulky or fluoro-containing substituents [21,22]. Fluorination is one of the most widely used methods to reduce the dielectric constant while lowering moisture absorption and improving solubility and optical properties [23e26].…”