High-optical transparency and low-dielectric constant of new organosoluble polyamides containing trifluoromethyl and xanthene groups

Abstract

A series of fluorinated polyamides was prepared directly by low-temperature polycondensation of a new cardo diacid chloride, 9,9-bis[4-(4-chloroformylphenoxy)phenyl]xanthene (BCPX), with various diamines containing trifluoromethyl substituents in N,N-dimethylacetamide (DMAc). Almost all polyamides showed excellent solubility in amide-type solvents such as DMAc and could also be dissolved in pyridine, m-cresol, and tetrahydrofuran. These polymers had inherent viscosities between 0.77 and 1.31 dL g−1, and their weight-average molecular weights and number-average molecular weights were in the range of 69,000–102,000 and 41,000–59,000, respectively. The resulting polymers showed glass transition temperatures between 240–258°C and 10% weight loss temperatures ranging from 484°C to 517°C and 410°C to 456°C in nitrogen and air, respectively, and char yields at 800°C in nitrogen higher than 55%. All polymers were amorphous and could be cast into transparent, light-colored, and flexible films with tensile strengths of 81–100 MPa, elongations at break of 8–12%, and tensile modulus of 1.6–2.1 GPa. These polymers had low-dielectric constants of 3.34–3.65 (100 kHz), low-moisture absorption in the range of 0.76–1.91%, and high transparency with an ultraviolet–visible absorption cut-off wavelength in the 322–340 nm range. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010