Poly-Schiff bases. V. Synthesis and characterization of novel soluble fluorine-containing polyether azomethines

A new dialdehyde monomer, 4,4′-(hexafluoroisopropylidine) bis(p-phenoxy) benzaldehyde, was prepared; it led to a number of novel poly-Schiff bases in reactions with different diamines, such as 4,4′-diaminidiphenyl ether, 4,4′-(isopropylidine) bis(p-phenoxy) dianiline, 4,4′-(hexafluoroisopropylidine) bis(p-phenoxy) dianiline, and benzidine. The polymers were characterized with viscosity measurements, nitrogen analyses, and IR and 1H NMR spectroscopy. These poly-Schiff bases showed good thermal stability up to 491 °C for 10% weight loss in thermogravimetric analysis under air and high glass-transition temperatures up to 215 °C in differential scanning calorimetry. These polymers were soluble in a wide range of organic solvents, such as CHCl3, dimethylformamide (DMF), dimethyl sulfoxide, and 1-methyl-2-pyrrolidon (NMP), and were insoluble in toluene and acetone. Thin films of these polymers cast from DMF exhibited tensile strengths up to 38 MPa.