Fluorinated diamines

More recently a new fluorinated diamine, 2,2 -bis(trifluoromethyl)-4,4 -diaminobiphenyl (BTDB), has been combined with HFDE and NE to provide a new PMR resin, PMR-12F-71, the chemical structure of which is provided in Fig. 36. The molar ratio of the reactants was adjusted such that a formulated molecular weight of 7100 g/mol was achieved. 

Furthermore, fluorinated diamines H2NCH2— (CF2)n—CH2NH2 and diisocyanates O = C = N — (CF2)n N = C = O have also been obtained. As in the case of the alcohols, all the diamines have a methylene group between the difluorome-thylene and the amine groups [9]. 

Ishii J, Tanaka Y, Hasegawa M. Film properties of polyazomethines (2). poly(imide-azo-methine)s derived from ester-containing dialdehydes, tetracarboxylic dianhydrides, and a fluorinated diamine. High Perform Polym 2010 22(2) 145-58. 

All of the newly developed fluorinated diamines and dianhydrides were targeted to prepare processable aromatic polyimides possessing many useful properties, such as high Tg, excellent dimensional stability, low dielectric constants, and outstanding thermal and thermo-oxidative stabilities. The combination of these properties leads the polyimides to be widely used as interlayer dielectrics, flexible circuitry substrates. 

Among various strategies that have been used to synthesize polyimides with lower dielectric constants, the most common approach is to incorporate fluorene, in the form of trifluoromethyl groups, into diamine and dianhydride units that minimize polarizability and increase the free volume [46]. It is well-known that fluorene atom has unique characteristics such as high electronegativity and low electric polarity. These properties give fluorinated polymers (e.g., poly[tetrafluoroethylene]) attractive features such as low water uptake, water and oil repellency, low permittivity, low refractive indices, resistance to wear and abrasion, and thermal and chemical stability. Fluorination is also known to enhance solubility and optical transparency and to lower the moisture absorption of polyimides. Therefore, it is expected that fluorinated polyimides will be widely applied in the electro-optical and semiconductor industries. The polymer series studied was essentially limited mainly to 6F dianhydride because it proved to be the only dianhydride with which many of the fluorinated diamines would form polymer films suitable for physical characterization. 

Between 2000 and 2010 a library of diamine structures to prepared fluorinated polyimides has been identified and prepared by several researchers. Some of the structures [58-63] are listed in Table 3.2. Ishida et al. prepared fluorinated diamine (3-1 in Table 3.2),... 

Banerjee et al, also prepared several diamine monomers [74-76] (3-20, 3-21, 3-22 in Table 3,3) with high FFV that were used for gas separation, and studied properties such as gas permeation and gas selectivities for several gas pairs, Banerjee et al, prepared high-Tg polymers by incorporating imido aryl [77] moiety (3-23 in Table 3,3) and further studied the gas separation properties, A fluorinated diamine monomer with anthracene moiety [78] (3-24 in Table 3,3) was also synthesized by Banerjee et al, the resulting polymers had high Tg values in the range 256-330 °C,... 

Jang et al. [85] prepared a highly kinked diamine (3-31 in Table 3.3), a fluorinated diamine (3-32 in Table 3.3), and a biphenyl based-fluorinated diamine (3-33 in Table 3.3) and studied the color intensity and optical properties of the synthesized polyimides. Introduction of kink structures disrupted effective CTC formation, leading to colorless polyimide films with high transmittance. Wang et al. [86] developed meta-diamine, namely 4,4 -/ /s (3-amino-5-trifluoro-methylphenoxy) biphenyl (3-34 in Table 3.3), with the aim of improving the melt processability and solubility of the polyimides. Shao et al. [87] designed a -CF3-substituted unsymmetrical diamine (3-35... 

Table 3.3 Chemical Structures of Fluorinated Diamines with Flexible Ether Linkages...

Behniafar et al. [101] prepared a new fluorinated diamine monomer (3-50 in Table 3.3) to improve the solubility and processability of polyimides, which they attributed to the high electronegativity of the... 

It is worth noting the Tg values of fluorinated polyimides (3-76 to 3-80 in Table 3.4) prepared by Banerjee et al. using different fluorinated diamines with ODPA as the dianhydride unit [119]. The following order of Tg is shown in Pig. 3.2 ... 

Yang et al. [121] synthesized a series of colorless poly(ether imide)s from BPADA and fluorinated diamines and investigated the solubility, thermal, mechanical, and optical properties. A representative structure of poly(ether imide) (3-81) is shown in... 

A further improvement in proton conductivity was accomplished by designing a new series of co-SPIs (DHNH-XX, where XX=40, 50, 60, and 70) using NTDA, DSDSA, and a flexible fluorinated diamine, l,4-(7i5(2 -trifluoromethyl-4 -[4"-aminophenyl]phe-noxy)benzene (HQA) [254], The repeat unit structure of the co-SPI is shown in Scheme 3.34(c). All of the DHNH-XX membranes showed high thermal stability (desulfonation temperature above 270 °C) and good mechanical properties (TS in the range... 

P. Velez-Herrera, H. Ishida, Synthesis and characterization of highly fluorinated diamines and benzoxazines derived therefrom, J. Ruo-rine Chem. 130 (6) (2009) 573-580. 

Zhao, Synthesis and characterization of soluble polyimides based on a new fluorinated diamine 4-phenyl-2,6-few[3-(4 -amino-2-... 

W. Jang, D. Shin, S. Choi, S. Park, H. Han, Effects of internal linkage groups of fluorinated diamine on the optical and dielectric properties of polyimide thin films. Polymer 48 (7)(2007) 2130-2143. 

---