PolyDADMAC coagulant, short for Polydiallyldimethylammonium Chloride coagulant, is a type of water-soluble cationic polymer widely used in water treatment processes as a coagulation and flocculation agent. 

This high molecular weight polymer has a strong positive charge due to the presence of quaternary ammonium groups (-N+(CH3)2), which makes it effective at neutralizing negatively charged particles such as suspended solids, colloids, and organic matter present in water.

In water treatment applications, when PolyDADMAC is added to the water, it attracts and binds to these negatively charged contaminants, forming larger aggregates called flocs. These flocs are more easily separated from the water through sedimentation or filtration processes, thus improving the clarity and quality of the treated water.

PolyDADMAC coagulants are often used in various sectors including drinking water purification, wastewater treatment, industrial process water treatment, and even in paper manufacturing as retention aids. It's known for its effectiveness across a wide range of pH levels and temperatures, making it versatile and adaptable to different treatment conditions.