Fluoro-containing poly(amide-imide)s with sterically hindered pendants: Synthesis and characterization

A structurally kinked fluorinated diacid, 2,6-bis(N-trimellitimido)-4-trifluoromethyl-4'-phenoxydiphenyl ether (TFPDPE) was synthesized and then used for preparing a new class of fluoro-containing poly(amide-imide)s via phosphorylation polyamidation with four diamines including 4,4'-(oxidianiline, 2,6-diamino-4-trifluoromethyl)-4'-phenoxydiphenyl ether, 1,5-bis(2-amino4-trifluoromethylphenoxy)-naphthalene, and 2,2'-bis(2-amino-4-trifluoromethylphenoxy)-1,1'-binaphthyl. Chemical structure of monomer TFPDPE as well as the resulted polymers was fully confirmed by IR and NMR spectroscopy. Limited viscosity numbers ([eta]'s) of the resulting polymers at 25 degrees C were measured. The values of (M) over bar (w) and (M) over bar (n) were determined using gel-permeation chromatography (GPC). In addition, the absorption edge values (lambda(0)) obtained from their UV curves were determined, and all the resulting poly(amide-imide)s exhibited high optical transparency. The crystallinity of the polymers was estimated by wide-angle X-ray diffraction (WXRD), and the resulted polymers exhibited nearly an amorphous nature. To study on the surface morphologies, the scanning electron microscopy (SEM) images of the poly(amide-imide)s were taken. Furthermore, solubility of the samples in various kinds of organic solvents was tested. From differential scanning calorimetric (DSC) analyses, the polymers showed Tg's between 304 and 328 degrees C. Thermo-stability of the polymers was determined by thermogravimetric analysis (TGA), and the 10% weight loss temperatures of the poly(amide-imide)s were found to be in the range of 548-553 degrees C. (C) 2012 Elsevier B.V. All rights reserved.