Poly(diallyldimethylammonium chloride) solution is widely used as a cationic polymer in water treatment processes. It acts as a flocculant, helping to aggregate suspended particles, making them easier to remove from water. This is particularly useful in municipal water treatment plants and industrial wastewater systems.

In the paper manufacturing industry, it serves as a retention aid and drainage enhancer. It improves the efficiency of the papermaking process by retaining fine particles and improving water drainage, leading to higher quality paper products.

The solution is also employed in the textile industry as a fabric softener and antistatic agent. It enhances the feel of fabrics and reduces static electricity, making textiles more comfortable to wear and handle.

Additionally, it is used in the cosmetics and personal care industry as a conditioning agent in hair and skin care products. It helps to improve the texture and manageability of hair while providing a smooth feel to the skin.

In biotechnology, it is utilized for DNA extraction and purification. Its cationic nature allows it to bind with DNA, facilitating its separation from other cellular components.

Overall, its versatility makes it a valuable component in various industrial and commercial applications.