Which tacticity form has alternating side groups along the chain?

• A. Isotactic
• B. Syndiotactic
• C. Atactic
• D. Random

Answer: (B)

Stereoregularity in polymers describes how pendant groups are arranged along the backbone. When the pendant groups alternate orientation from one repeat unit to the next, the pattern repeats every two units. This alternating arrangement is called syndiotactic. It contrasts with isotactic, where all substituents lie on the same side, and atactic, where the orientation is random. The term “random” implies no regular pattern, which is not the alternating arrangement described here. The regular alternating pattern of syndiotactic can influence how the chains pack and, in turn, the material’s properties.