Two types of new fluorinated diamine monomer, [1,4-(4-amio-2-trifluoromethyl-phenoxy)-2-(3'-trifluoromethylphenyl) benzene (III)] and [1,4-(4-amio-2-trifluoromethyl-phenoxy)-2-(3'-methylplienyl) benzene (IV)] were synthesized and polymerized with aromatic dianhydrides. A series of soluble poly(ether imide)s (PEIs) were prepared from the diamines and dianhydrides by two-step chemical imidization methods. Experimental results indicated that all the PEIs had glass transition temperature between 230 degrees C and 247 degrees C, the temperature at 5% weight loss between 527 degrees C and 598 degrees C under nitrogen. The membranes hand tensile strengths in the range of 74-101 MPa, tensile modulus in the range of 1.9-2.6 GPa, and elongation at break from 20 to 28%. The cast membranes also exhibited high optical transparency, with a UV-vis absorption edge of 354-406 nm. Moreover, these PEIs membranes possessed low dielectric constants of 2.63-3.20 (at 1 MHz) and low water uptakes (<0.75 wt%). (C) 2008 Elsevier Ltd. All rights reserved.