Poly with trifluoromethyl group

A large variety of newer poly(ether imide)s has been described. Included among these are perfluorinated polymers (96), poly(ester ether imide)s (97), poly(ether imide)s derived from A/,Ar-diamino-l,4,5,8-naphthalenetetracarboxyHcbisimide (98), and poly(arylene ether imide ketone)s (99). In addition, many other heterocyHc groups have been introduced into polyether systems, eg, poly(pyrazole ether)s (100) and poly(aryl ether phenylquinoxaLine)s (101) poly(aryl ether oxazole)s with trifluoromethyl groups (102) and polyethers with other heterolinkages, eg, poly(arylether azine)s (103). 

I.S. Chung, K.H. Kim, YS. Lee, S.Y. Kim, Poly(arylene ether)s with trifluoromethyl groups via meta-activated nitro displacement reaction. Polymer 51 (20) (2010) 4477-4483. 

Under special conditions it is possible to prepare PEDT films of more than 20 m length [64]. For such films suitable polyanions, e.g. sulfated poly(/3-hydroxyether)s or poly(hydroxyether)s bearing trifluoromethyl groups and sulfated poly(buta-diene)s are necessary. The preparation can be achieved on cylindrical electrodes of a computer controlled system. The electrical conductivity of such PEDT materials with the above mentioned polyanions composites exceed 150Scm , and reaches as high as 400Scm if the polyester with trifluoromethyl groups is used. Such films are used for the production of batteries (see section 10.5) [64]. 

Recently, Baneijee et al. prepared a series of difluoro monomers with pendent trifluoromethyl groups using a Pd(0)-catalyzed cross-coupling reaction (Scheme 6.32).242,243 These monomers were converted to poly(arylene ether)s by nucleophilic displacement of the halogen atoms on the benzene ring with several... 

The processability of fluorine-containing polymers is improved by replacement of one or more of the fluorine atoms. Replacing one of the eight fluorine atoms with a trifluoromethyl group gives a product called FEP or Viton, actually a copolymer of tetrafluoroethylene and hexafluoropropylene (Equation 6.53). Polytrifluoromonochloroethylene (PCTFE, Kel F) (Equation 6.54), in which one fluorine atom has been replaced by a chlorine atom, has a less regular structure and is thus more easily processed. Poly(vinylidene fluoride) (PVDF, Kynar) (Equation 6.55) is also more easily processable but less resistant to solvents and corrosives. 

As shown in Scheme 29, aromatic and vinylic dithioester groups can be converted to trifluoromethyl groups directly by treating them with (Bu4N)H2p3-DBH (l,3-dibromo-5,5-dimethylhydantoin) (Path a) [17]. The use of NBS or NCS (Path b) in place of DBH yields a,a-difluoro sulfides 130 [17]. This fluorination can also be performed with poly(hydrogen fluoride) pyridinium (Path c) [32]. 

Poly(biphenylene-1,3,4-oxadiazole) and poly(biph-enylene hydrazide) with the electron-withdrawing tri-fluoromethyl group have been synthesized. The bulky trifluoromethyl group effects a non-coplanar conformation of the chain [57]. 

I.S. Chung, S.Y Kim, Meta-activated nucleophilic aromatic substitution reaction poly(biphenylene oxide)s with trifluoromethyl pendent groups via nitro displacement, J. Am. Chem. Soc. 123 (44) (2001) 11071-11072. 

S.D. Kim, D. Ka, I.S. Chung, S.Y. Kim, PoIy(arylene ether)s with low refractive indices poly(biphenylene oxide)s with trifluoromethyl pendant groups via a meto-activated Nitro displacement reaction. Macromolecules 45 (7)(2012) 3023-3031. 

S. Banerjee, G. Maier, M. Burger, Novel Poly(arylene ether)s with pendent trifluoromethyl groups. Macromolecules 32 (13) (1999) 4279 289. 

K. Tsuchiya, Y. Shibasaki, M. Aoyagi, M. Ueda, Synthesis of a novel poly(binaphthylene ether) containing trifluoromethyl groups with a low dielectric constant. Macromolecules 39 (11)(2006) 3964-3966. 

F. Schonberger, A. Chromik, J. Kerres, Synthesis and characterization of novel (sulfo-nated) poly(arylene ether)s with pendent trifluoromethyl groups, Polymer 50 (9) (2009) 2010-2024. 

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. 

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