Synthesis and characterization of new aramids based on o-(m-triphenyl)-terephthaloyl chloride and m-(m-triphenyl)-isophthaloyl chloride

Two monomers o -( m -triphenyl)-terephthaloyl chloride (TPH1-COCl) and m -( m -triphenyl)- isophthaloyl chloride (TPH2-COCl) with bulky pendant groups were prepared, and they were polymerized with p -phenylenediamine (PPD) or copolymerized with PPD and terephthaloyl chloride (TPC) to prepare aromatic polyamides which were named TPH1 polymer and TPH2 polymer, respectively. The structures of the monomers with bulky pendant groups and the polymers were characterized by 1 H NMR and gel permeation chromatography . The resulting polymers are soluble in some organic solvents such as N -methyl-2-pyrrolidone. However, the solubility of the two series of polymers was different due to the different structures of the two monomers, and it is affected by the feeding ratio of the monomers. Both kinds of polymers have good thermal stabilities with 5% weight loss temperatures close to 500 °C. And glass transitions of some TPH2 polymers were observed. Most of these polyamides show lyotropic liquid crystalline (LLC) behaviors as evidenced by polarized light microscopy results. And the LLC properties are influenced by the structures, molecular weights , and concentrations of the polymers.