Synthesis and optical properties of novel soluble and optically transparent semifluorinated poly (ether imide)s

Abstract

A fluorinated diamine monomer containing flexible ether linkage and bulky trifluoromethyl substituents, namely, bis(4‐amino‐2‐trifluoromethylphenyl) ether (a), is employed to react with nonfluorinated 1,4‐bis(3,4‐dicarboxyphenoxy) benzene dianhydride (3) and CF3‐free 2,2‐bis[4‐(3,4‐dicarboxyphenoxy)phenyl] propane dianhydride (4), respectively, to prepare 2 novel soluble and optically transparent semi‐fluorinated poly (ether imide)s (PEIs; 3a and 4a). Compared with the corresponding PEIs based on nonfluorinated 4,4′‐diaminodiphenyl ether (b) and CF3‐free pyromellitic dianhydride (5), the novel semifluorinated PEIs 3a and 4a not only display better solubility in some organic solvents and higher optical transparency with cutoff absorption wavelength (λ0) below 370 nm but also maintain outstanding mechanical properties and thermal stability. 3a and 4a have tensile strength beyond 80 MPa and possess glass‐transition temperatures (Tg) beyond 210°C, coupled with the temperatures of 5% weight loss (T5%) exceeding 500°C. It is also found that 3a and 4a exhibit contact angles against water beyond 110° and water absorptions below 0.8% together with dielectric constants less than 3.2.