Synthesis and properties of novel soluble polyimides having a spirobisindane-linked dianhydride unit

A new synthetic procedure was elaborated allowing the preparation of semiaromatic dianhydride. N-Methyl protected 4-chlorophthalic anhydride was nitrated with HNO3 to produce N-methyl-4-chloro-5-nitrophthalimide (1). The aromatic nucleophilic substitution reaction between 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1-spirobisindane and 1 afforded spirobisindane-linked bis(N-methylphthalimide) (2), which was hydrolyzed and subsequently dehydrated to give the corresponding dianhydride (3). The latter was polymerized with five different aromatic diamines to afford a series of aromatic polyimides. The properties of polyimides such as inherent viscosity, solubility, UV transparency and thermal stability were investigated to illustrate the contribution of the introduction of spirobisindane groups into the polyimide backbone. The resulting polyimides were readily soluble in polar solvents such as chloroform, THF and N-methyl-2-pyrrolidone. The glass-transition temperatures of these polyimides were in the range of 254-292 degrees C. The tensile strength, elongation at break, and Young's modulus of the polyimide film were 68.8-106.6 MPa, 5.9-9.8%, 1.7-2.0 GPa, respectively. The polymer films were colorless and transparent with the absorption cutoff wavelength at 286-308 nm.

Synthesis and characterization of novel polyimides from alicyclic dianhydride

New alicyclic Polyimides (PIs) were prepared from asymmetric alicyclic dianhydride, 5-(2,5-dioxotetrahydrofuryl)-3-methyl-cyclohexane-1,2-dicarboxylic anhydride (DOCDA) and the corresponding aromatic diamines such as p-phenylenediamine, m-phenylenediamine and oxydianiline etc. by the polycondensation in N-methyl-2-pyrrolidone (NMP) followed by chemical imidization as well as one step polyimidization in m-cresol in the presence of isoquinoline as a catalyst. The resulting PIs with glass transition temperatures ranging from 220 to 328 degrees C had the inherent viscosities within the range of 0.25 similar to 1.42 dL/g. These polymers were readily soluble in aprotic polar solvents such as NMP, dimethylacetamide (DMAc), dimethylesulfoxide (DMSO), etc. Furthermore, some of the polymers showed good solubility properties to common organic solvents like tetrahydrofurane and chlorform. Also, all of these polyimide films were tough, almost colourless, and transparent.