A substance that can reduce the surface tension of water, solutions, suspensions, etc., prevent foam formation, or reduce or eliminate existing foam.^[1]

Defoamers should possess the following properties: ① Strong defoaming power with low dosage; ② Addition to the foaming system does not affect the basic properties of the system, meaning it does not react with the defoamed system; ③ Low surface tension; ④ Good surface balance; ⑤ Good heat resistance; ⑥ Good diffusivity and permeability, with a high positive spreading coefficient; ⑦ Chemically stable with strong oxidation resistance; ⑧ Good gas solubility and permeability; ⑨ Low solubility in foaming solutions; ⑩ No physiological activity and high safety.^[2]

Defoamers are widely used in industries such as food processing, paper manufacturing, water treatment, petroleum extraction, printing and dyeing, coatings, detergent production, rubber latex processing, aerosol production, daily chemical manufacturing, pharmaceuticals, and dairy production.