Synthesis and Characterization of Soluble Cardo Poly(ester-imide)s Derived from 9,9-Bis[4-(3,4-dicarboxybenzoyloxy)phenyl]fluorene

A novel fluorenyl cardo dianhydride-9,9-bis4-(3,4-dicarboxybenzoyloxy)phenyl]fluorene (BDPF) was synthesized and characterized. A series of fluorenyl cardo poly(ester-imide)s (FCPEIs) were prepared by the polycondensation of BDPF with m-phenylene diamine, 4,4′-oxydianiline (4,4′-ODA), 3,4′-oxydianiline (3,4′-ODA), 2,2-bis4-(4-amino -phenoxy)phenyl]propane, 2,2-bis4-(4-aminophenoxy)phenyl]hexafluoropropane, and 1,6-hexamethylenediamine. Most of the FCPEIs exhibited excellent solubility in common organic solvents such as 1,2-dichlorobenzene (o-DCB), chloroform, tetrahydrofuran, N,N-dimethylacetamide (DMAc), dimethyl sulfoxide, N-methyl-2-pyrrolidinone, etc. Intrinsic viscosities of FCPEIs in DMAc, for instance, ranged from 0.29–0.52 dL/g. The glass transition temperature of these polymers was between 199°C and 283°C by differential scanning calorimentry, and the 5% weight loss temperature of all polymers exceeded 400°C in air.