Effects of Diamines on the Optical Properties of Poly(ether imide)s Derived from 2,2-Bis4-(3,4-dicarboxyphenoxy)phenylpropane Dianhydride (BPADA)

摘要

The objective of this study was to investigate the effects of diamines with ether group or/and trifluoromethyl (-CF3)group on the optical properties of polyimides. A series of poly(ether imide)s (PEIs) (III) were prepared from 2,2-bis4-(3,4-dicarboxy-phenoxy)phenylpropane dianhydride (BPADA) with various aromatic diamines (Ia-h) including non-fluorinated diamines (Ia-d) and the corresponding trifluoromethyl-substituted diamines (Ie-h). The fluorinated PEIs IIIe-h based on fluorinated diamines were nearly colorless with cutoff absorption wavelength (lambda(0)) below 370 nm and with solubility higher than that of the corresponding CF3-free analogues (IIIa-d). Meanwhile, they had lower dielectric constants in the range of 2.91-3.21 at 1 MHz coupled with water absorptions below 0.70 and contact angles against water beyond 108 degrees. The III series had tensile strength of 84.3-94.4 MPa, modulus of elasticity of 3.6-8.9 GPa and elongation at break of 9.4-25.3, together with temperatures of 5 weight loss (T-5) beyond 510 degrees C. Compared to the IV series based on 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), the corresponding III series exhibited better thermal and mechanical properties coupled with good optical properties, especially the fluorinated PEIs IIIe-h.