Preparation and Properties of Novel Aromatic Polyamides from Diamines Containing 4,5-Imidazolediyl Structure

Novel aromatic polyamides were prepared from aromatic diamine containing 4,5-imidazolediyl unit, either by low temperature solution polycondensation or by direct polycondensation. Used diamines were 4,5-bis(4-aminophenyl)-2-phenylimidazole 1, 4,5-bis[4-(4-aminophenyl)]-2-(4-methylphenyl)imidazole 2 and 4,5-bis[4-(4-aminophenoxy)phenyl]-2-phenylimidazole 3. The obtained aromatic polyamides were produced with moderate to high inherent viscosity and soluble in polar aprotic solvents such as N,N-dimethylacetamide (DMAc), 1-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). Thermogravimetric analysis showed those polymers were stable up to 422°C in nitrogen atmosphere. The glass transition temperature (T _g)s of the polymers derived from diamine 3 were in the range between 243 and 275°C, and these values were approximately 120–160°C lower than those analogue polyamide I series containing no phenoxy units. The properties of polyamide I series are also compared with those of analogue polymers that order of aromatic nuclei and amide linkage is reversible.