Pendent aromatic group

Structural modifications to attain soluble aromatic polyimides have also been carried out by introducing bulky substituents, aryl or heterocyclic rings. One of the first references to this approach was made by Korschak and Rusanov, who synthesized soluble aromatic polyimides containing side phthalimide groups [85 ]. More recent work by Rusanov et al. has enriched this topic with new soluble polyimides containing pendent imide groups [86,87]. 

PI types that are built from 2,4,6-trimethyl-1,3-phenylenediamine and 3,3, 4,4 -benzophenone tetracarboxylic dianhydride are photochemically crosslinkable due to the benzophenone incorporated. It is essential that pendent alkyl groups are attached to the aromatic structure. " However, it has been objected that photochemical crosslinking is not a practical method for fabricating gas separation membranes cost-effectively. ... 

C.-P. Yang, Y.-Y. Su, and Y.-C. Chen. Colorless poly(elher-iniide)s deriving from 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride (BPADA) and aromatic bis(ether amine)s bearing pendent trifluoromethyl groups. Eur. Polym. J., 42(4) 721-732, April 2006. 

Polybenzimidazoles with pendent acidic groups sulfopropylated polybenzimidazole [31], sulfonated polybenzimidazole by the grafting of (4-bromomethyl)benzenesulfonate onto PBI [32], phosphonated fuUy aromatic polyethers containing pyridine building blocks [33], sidfraiated aromatic polyethers containing pyridine units [34], sulfonated polybenzimidazoles from sulfonated dicar-boxylic acid monomers [35-37]. 

Li claims to have reacted the sulfonated polymer 13 further in a Friedel-Crafts reaction with aromatics to give polymers with pendent sulfone groups. 

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