A series of new fluorinated rigid-rod polyimides have been synthesized by the reaction of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFDB) with l,4-bis(trifluoromethyl)-2,3,5,6-benzenetetracarboxylic dianhydride (P6FDA), 1 -(trifluoromethyl) -2,3,5,6-benzenetetracarboxylic dianhydride (P3FDA), or pyromellitic dianhydride (PMDA). The dielectric constant, refractive index, and water absorption decrease with an increasing number of trifluoromethyl side chains. The polyimide P6FDA/TFDB with the highest fluorine content prepared from TFDB and P6FDA has the lowest dielectric constant of 2.6 at 1 MHz, the lowest refractive index of 1.490 at 589.3 nm, and the lowest water absorption of 0.38%. On the other hand, the coefficient of thermal expansion (CTE) increases with an increasing number of trifluoromethyl side chains. The polyimide PMDA/TFDB prepared from TFDB and PMDA has a negative CTE of-5 x 10-6 °C~1 by thermomechanical analysis (TMA) and a high polymer decomposition temperature of 613 °C measured for a 10% weight loss in a nitrogen atmosphere by thermogravimetric analysis (TGA).
A series of new polyimides containing fluorinated alkoxy side chains are prepared from novel fluorinated alkoxy diamines. The dieletric constant at 1 kHz in the fluorinated polyimides decreases from 3.3 to 2.6 as fluorine content increases. The refractive index also changes from 1.58 to 1.48, dependent on the fluorine content. In addition, the fluorinated polyimides exhibit lower water absorption than the reference polyimides prepared from m‐phenylenediamine.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.