Synthesis of fluorinated poly(phenylquinoxaline-amide)s and study of thin films made therefrom

A series of five fluorinated poly(phenylquinoxaline-amide)s were synthesize d by a polycondensation reaction of a diacid chloride containing the hexafl uoroisopropylidene (6F) group, namely 2,2-bis(p-chlorocarbonylphenyl)-hexaf luoropropane, with various aromatic diamines incorporating two phenyl-subst ituted quinoxaline rings. These polymers were easily soluble in polar aprot ic solvents such as N-methyl-pyrrolione (NMP), dimethylformamide (DMF), and tetrahydrofurane (THF), and showed a high thermal stability with decomposi tion temperatures above 400 degrees C and glass transition temperatures in the range of 260-290 degrees C. Polymer solutions in NMP were processed int o free-standing films that showed low dielectric constant values, in the ra nge of 3.4-3.9, and good mechanical properties, with tensile strength in th e range of 40-80 MPa and elongation to break in the range of 22-55%. Very t hin films, in the range of tens of nanometer, which were deposited onto sil icon wafers exhibited very smooth surfaces, free of pinholes when studied b y atomic force microscopy (AFM). (C) 1999 Elsevier Science Ltd. All rights reserved.