Triptycene Polyimides: Soluble Polymers with High Thermal Stability and Low Refractive Indices

A series of sol., thermally stable arom. polyimides were synthesized using com. available five- and six-membered ring anhydrides and 2,6-diaminotriptycene derivs. All of these triptycene polyimides (TPIs) were sol. in common org. solvents despite their completely arom. structure due to the three-dimensional triptycene structure that prevents strong interchain interactions. Low soln. viscosities (0.07-0.47 dL/g) and versatile solubilities allow for easy soln. processing of these polymers. Nanoporosity in the solid state gives rise to high surface areas (up to 430 m2/g) and low refractive indexes (1.19-1.79 at 633 nm), which suggest very low dielec. consts. at optical frequencies. Polymer films were found to be amorphous. The decompn. temp. (Td) for all of the polymers is above 500°, and no glass transition temps. can be found below 450° by differential scanning calorimetry (DSC), indicating excellent prospects for high-temp. applications. This combination of properties makes these polymers candidates for spin-on dielec. materials. [on SciFinder(R)]