Polyquaternium-39 is widely used in hair care products such as shampoos, conditioners, and styling products due to its excellent conditioning and anti-static properties. It helps to smooth the hair cuticle, reduce frizz, and improve manageability, making it a popular ingredient for enhancing hair texture and appearance. Additionally, it is effective in skin care formulations, where it acts as a moisturizing agent, helping to retain hydration and improve skin softness. Its film-forming ability also provides a protective barrier on the skin and hair, shielding them from environmental stressors.