In this study : flexible nylon 6 vias reinforced by the following rigid-chain aromatic polyamides : poly(m-phenylene isophthalamide)(PmIA), poly(4,4＇-diphenylsulfone terephthalamide) (PSA), poly(p-diphenyloxide terephthalamide)(POA), and poly(p-diphenylmethane terephthalamide) (PMA). Various high-molecular-weight block copolyamides were synthesized by solution polymerization using p-aminophenylacetic acid (p-APA) as a coupling agent. Their thermal properties have shown that the block copolyamides exhibit higher T-g and T-m and better thermal stability than those of nylon 6, especially PmIA-modified nylon 6. The order of their thermal properties of aromatic modified nylon 6 copolyamides is PmIA > PMA > POA > PSA. Besides, the T-g and T-m of multiblock copolyamides are higher than those of triblock copolyamides. From the wide-angle X-ray diffraction pattern, it is found that the triblock copolyamides have two diffraction peaks (i.e., 2 theta = 20.5 and 24 degrees). However, the multiblock has only one at 2 theta = 20 degrees, indicating a different crystal structure for multiblock copolyamides. This can be further confirmed from scanning electron microscopy. It shows that the triblock copolyamides are a dispersed phase structure, although the multiblock copolyamides exhibit a homogeneous texture rather than an aggregated one. For the mechanical properties, it is found tl-lat the multiblock copolyamides have a more significant reinforcing effect than the triblock copolyamides. Also, the order of their physical properties of aromatic modified nylon 6 copolyamides, such as tensile strength, is PmIA > PMA > POA > PSA; but for the elongation, the order is PSA > POA > PMA > PmIA.