Cardo polymer

These are a special group [201, 208, 220] of polymeric materials. The name cardo comes from Latin, meaning loop [201, 208]. The polymers contain cyclic structures that may be perpendicular to the aromatic backbones. An example would be a cardo polybenzimidazole  

Many cardo polymers exhibit improved solubility in different solvents with little sacrifice in properties. A survey was made of the physical properties of different cardo copolyimides with varying microstructures [220]. As might be expected, copolyimides with increasing aliphatic fragment content were shown to exhibit the highest impact and flexural strength. 

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Diaryl phthalides, particularly phenolphthalein 281 and several phthalides derived from it, are widely used for the preparation of cardo polymers. The term is derived from the latin word for hinge or pivot, which is an apt name given that the aryl substituents are hinged on the C-3 carbon of the phthalide. In one application, compound 281 was used to prepare phthalamide 282 and both bisphenols were copolymerized with terephthaloyl chloride 283 to form polyesters. These formed strong flexible fdms with improved thermal stability and solubility <1997PSA3227>. 

What are cardo polymers, what are their advantages, and how are they prepared ... 

Korshak VV, Vinogradova SV, Vygodskii YS. Cardo polymers. J Macromolecular Sci Part C Polym Rev 1974 11(1) 45-142. 

S. Kazama, T. Teramoto, K. Haraya, Carbon dioxide and nitrogen transport properties of w(phenyl)fluorene-based cardo polymer membranes, J. Memb. Sci. 207 (1) (2002) 91-104. 

K. Miyatake, B. Bae, M. Watanabe, Ruorene-containing cardo polymers as ion conductive membranes for fuel cells, Polym. Chem. 2 (9) (2011) 1919-1929. 

Chen, D. Hickner, M. A. Wang, S. Pan, J. Xiao, M. Meng, Y, Synthesis and characterization of quaternary ammonium functionalized fluorene-containing cardo polymers for potential anion exchange membrane water electrolyzer applications. International Journal of Hydrogen Energy 2012, 37(21), 16168-16176. 

Recently, polyimines include the synthesis of long alkoxy (Cg-Cig) side chain derivatives [188,189], which are presumably soluble to some extent in organic solvents and derivatives containing fluorene cardo unit [190]. Trifluoromethyl groups [191] in the polymer backbone provide solubility in organic solvents. Studies of the electrical conductivity of doped conjugated aromatic polyimines and alkoxy derivatives have been reported [188], and the values are in the range of 10 to 10 S/ cm. 

These solubility enhancing side groups are termed cards, with the corresponding polymers called cardo-polyimides [29]. Solubility of the polyimides can also be improved by the use of fluorinated monomers and monomers containing flexible linkages. Sillion and others have used soluble cardo-polyimides in their quest towards incorporating reactive polyimides into epoxy but they... 

PEEK polymers are characterized by a high crystallinity which can be reduced by PEEK modified with cardo (Latin meaning loop) group which increase the amorphous degree. Sulfonated cardo-group modified PEEK (sPEEK-WC), as shown in Fig. 6.7, has been proposed for DMFC application [182-184]. A comprehensive review of the use of sPEEK and sPEEK-WC membranes in DMFC has been recently performed by lulianelli and Basile [185]. 

Many kinds of AEMs based on quatemized polymers containing a quaternary ammonium group have been developed and tested in ADAFC, such as polyethersulfone cardo (QPES-C) [205], polyetherketone cardo (QPEK-C) [206], poly (phthalazinone ethersulfone ketone) (QPPESK) [207], poly(arylene ethersulfone) (QPAES) [208-210], QPAES cross-linked with tetraphenylolethane glycidyl ether (QPAES/4EP) [210], poly (arylether oxadiazole) (QPAEO) [211], poly styrene-block-poly (e thy lene-ran-butylene)-block-poly styrene (QSEBS) [212], poly(vinyl alcohol) (QPVA) [213], poly(vinyl chloride) (QPVC) [214], and poly (vinylbenzyl chloride) (QPVBC) [215]. The chemical structures of some of these polymers are shown in Fig. 6.13. 

Banerjee et al. [60] also prepared fluorinated copoly(arylene ether)s by incorporating different molar ratios of A-phenyl-3,3-( w(4-hydroxyphenyl) phthalimidine (Scheme 2.11) in the polymer structure and studied the Tg. It was observed that with an increase in the amount of phthalimidine moiety, the Tg increased because of the rigid cardo structure. The copolymer with highest bisphenol A content had an EB as high as 45% as a result of the increase in flexi-bilizing isopropylidene units. 

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