Investigations on the polyimides derived from unfunctionalized symmetric cyclopentyl‐containing alicyclic cardo‐type dianhydride

This study presents an investigation on polyimides derived from a unfunctionalized symmetric cyclopentyl-containing alicyclic cardo-type dianhydride with ester linkage 1,1-bis(4-(3,4-dicarboxylbenzoyloxy)phenyl) cyclopentylene dianhydride (BDPCP) that was readily accessed starting from cyclopentanone through two steps in high yield. Two series of polyimides, Cardo-type series (CPI-x) and analogous aromatic series (ArPI-x) were prepared from condensation of BDPCP and aromatic 3,3',4,4'-Oxydiphthalic dianhydride with four aromatic diamines, respectively. Comparative studies revealed that CPI polymers show more favorable properties including better solubility in organic solvents, higher transparency with lower cut-off wavelength (lambda(0)) ranging in 395-375 nm than 425-405 nm, lower water absorption ranging in 0.66-1.14% and surface energy 23.71-32.77 mN/m than 1.01-1.28% and 29.52-41.99 mN/m of ArPI analogs. Meanwhile, CPI series exhibit considerable mechanical properties with tensile strengths ranging in 87.6-102.9 MPa, elongations at break 6.6-8.9%. Owing to the moderate strain in cyclopentyl ring, CPI series retain good thermal properties with the glass transition temperature (T-g) in the range of 217-271 degrees C. Dynamic dielectric measurement revealed that Cardo-type dianhydride BDPCP endows CPI-4 film with lower dielectric constant (epsilon') 3.34 at 1 MHz and 25 degrees C and dielectric loss (epsilon '') 0.0064 at 1 kHz and 25 degrees C than 3.49 and 0.013 for ArPI-4 film. (C) 2015 Wiley Periodicals, Inc.