New autophotosensitive semiaromatic hyperbranched polyimides with excellent thermal stabilities and low birefringences

A series of autophotosensitive semiaromatic hyperbranched polyimides were prepared by (A(2) + B-3)-type method and endcapped with 3-aminophenylacetylene. The photosensitive-hyperbranched polyimides (PHBPIs) showed excellent solubility, excellent optical properties, and low birefringences in the range of 0.0010-0.0027, caused by their special hyperbranched structures and alicyclic chain segments reduced both intramolecular and intermolecular charge transfer complex effect. The cured films also showed high glass transition temperatures between 204 degrees C and 220 degrees C, excellent thermal stabilities with 10% thermal decomposing temperatures in the range of 476-495 degrees C, and good mechanical properties. The PHBPIs had photosensitivities (D-g) in the range of 80-162 mJ/cm(2) and showed a clear negative image with a line width of 8 mu m when exposed to an ultraviolet light of 365 nm (i-line).