Synthesis and Properties of Fluorinated Polyimides from Rigid and Twisted Bis(Trifluoromethyl)Benzidine for Flexible Electronics

Abstract

Fluorinated polyimides were prepared from the twisted benzidine monomer containing two trifluoromethyl (CF 3) groups on one aromatic ring. The diamine monomer having a rigid and nonplanar structure was polymerized with typical dianhydride monomers including BPDA, BTDA, ODPA, 6-FDA, and PMDA, to obtain the corresponding polyimides. Most polyimides are soluble in organic solvents due to their twisted chain structure and can be solution cast into flexible and tough films. These films have a UV-vis absorption cutoff wavelength at 354-398 nm and a light transparency of 34-90% at a wavelength of 550 nm. They also have tensile strengths of 92-145 MPa and coefficients of thermal expansion (CTE) of 6.8-63.1 ppm/°C. The polymers exhibited high thermal stability with 5% weight loss at temperatures ranging from 535 to 605°C in nitrogen and from 523 to 594°C in air, and high glass temperature (T g) values in the range of 345-366°C. Interestingly, some of the soluble polyimides showed thermo-responsive behaviors in organic solvents presumably due to the multiple hydrogen bondings with unsymmetrically positioned two CF 3 groups along the polymer chains.

Direct ink writing of polyimide aerogels for battery thermal mitigation

“…The sample at 0 min of reaction time is the same for both untreated and heated sols. The intensity of the peak corresponding to the imide CO stretching (1724 cm −1 ) relative to the intensity of the peak corresponding to the C–F bond (1172 cm −1 ) 94,95 is compared in Fig. S2 †.…”

Structural Designs of Transparent Polyimide Films with Low Dielectric Properties and Low Water Absorption: A Review

“…Furthermore, PIs have excellent mechanical properties, including high moduli and tensile strength, which facilitate their use in the wide −270 to +300 °C temperature range [ 31 ]. Even though PIs have suitable properties for high-speed communications, they have some drawbacks, including poor solubility in organic solvents, infusibility, and strong coloration due to charge-transfer-complex (CTC) formation [ 32 , 33 , 34 ].…”

Intrinsic low‐dielectric‐constant polyimides based on a novel diamine having −CF3 groups and kinkable 1,4‐diisopropylbenzene units

“…One outstanding methodology involves modifying the main chain of PIs by adding extra methyl and/or trifluoromethyl groups to form contour polyetherimides. [21][22][23][24] This approach increases the free molar volume while reducing the molar polarizability of the PI chains, making the resulting PI a useful low-dielectric material. 22 In this regard, 4,4 0 -(1,4-phenylenebis(propane-2,2-diyl))diphenoxybis(2-(trifluoromethyl)-4-aminobenzene) (BPBTAB), a new nonplanar diamine molecule with a 1,4-diisopropylbenzene unit and two trifluoromethyl groups, was designed and synthesized, followed by the synthesis of a series of novel PIs (named BPBTAB-X PI), where X is either PMDA, BPDA, 1,2,3,4cyclobutanetetracarboxylic dianhydride (CBDA) or 4,4 0 -(hexafluoroisopropylidene)diphthalic anhydride (FDA).…”

“…The design of low‐dielectric transparent PIs has been explored in numerous studies. One outstanding methodology involves modifying the main chain of PIs by adding extra methyl and/or trifluoromethyl groups to form contour polyetherimides 21–24 . This approach increases the free molar volume while reducing the molar polarizability of the PI chains, making the resulting PI a useful low‐dielectric material 22 …”