Various polysulfonamide （PSA） statistical copolymers were synthesized by polycondensation of three aromatic diamines and terephthaloyl chloride. The inherent viscosities of the resulting PSA copolymers range from 1.54 to 1.66 dL/g. The precipitated PSA copolymers with feed content of p-phenylene diamine （PPD） being less than 50% （mole fraction） can be redissolved in N-methyl-2-pryrrolidone （NMP） or N, N-dimethylacetamide （DMAc） with lithium chloride of WLiC1 ： 0.02. All of the PSA copolymers exhibit enhanced tensile strength in comparison with PSA and still maintain excellent thermal stability in either air or nitrogen atmosphere
