In this study, first 2,2'-(1,4-phenylene)bis(4,5-dihydrothiazole-4-carboxylic acid was prepared from the reaction of 1,4 -dicyanobenzene and L-cysteine in water and methanol. The structure of the synthesized diacid was characterized by FT-IR, 1HNMR, 13CNMR and elemental analysis. Then, some new polyamides (PAs) were synthesized by polycondensation of diacid and different aromatic diamines in tetra butyl ammonium bromide ionic liquid and triphenylphosphate as catalyst. The resulting PAs exhibited good yields, high thermal stability with inherent viscosities ranging between 0.23 and 0.30 dL/g and was soluble in polar aprotic solvents such as DMSO, DMAc, NMP and DMF. The optical properties of the synthesized polymers were measured. The structure of the synthesized polymers was identified by FT-IR, 1HNMR, elemental analysis and thermogravimetric analysis. The morphology and structure of the polymers were determined by FE-SEM and XRD methods. Also, the antibacterial properties of these polymers were determined by dilution method for two species of Escherichia coli and Staphylococcus aureus as known samples of gram-negative and gram-positive bacteria.