Surfactants for Polyurethane Foam
Surfactants are essential additives in polyurethane foam production. They emulsify the raw materials, regulate cell formation, stabilise the rising foam and control cell size — giving a fine, uniform and stable foam structure for both flexible and rigid PU foam.
What Surfactants Do in PU Foam
In polyurethane systems, surfactants — most often silicone–polyether copolymers — play several key roles:
Emulsification: blend polyol, isocyanate, water, catalysts and additives into a uniform mix.
Cell nucleation & regulation: control the number and size of gas bubbles for a fine, even cell structure.
Foam stabilisation: reinforce cell walls during rise to prevent collapse, splits or coarse cells.
Flow & surface: improve mould filling, surface finish and the final foam’s physical properties.
Surfactants are one part of a complete polyurethane system, working with the polyol and isocyanate — see our MDI and TDI isocyanates.
Why Choose Us
Types of Surfactants
Surfactants for polyurethane foam are chosen by foam type and the properties you need. Silicone surfactants (silicone–polyether copolymers) are by far the most widely used: high-activity grades for rigid foam give fine, closed cells and good flow, while milder grades for flexible foam give open, breathable cells and good stability. Non-silicone surfactants (polyether, anionic, cationic and amphoteric) are used where special wetting, antistatic or compatibility properties are required. The common types are summarised below.
Surfactants are matched to the foam they go into — explore our flexible foam, rigid foam and spray foam material ranges.
Common types of surfactants used in PU
In the polyurethane production process, surfactants play a key role and are mainly used to regulate the formation and stability of foam. Common types of surfactants include:
Amphoteric surfactants:
· Function: Depending on the acidity and alkalinity of the solution, these surfactants can be anionic or cationic, with good compatibility and mild properties, and are often used in polyurethane products that require special properties.
· Cocamidopropyl betaine (CAPB): This is a common amphoteric surfactant with mild properties and is widely used in personal care products, but its application in the polyurethane industry is relatively rare.
Polyether surfactants:
· Function:It has good emulsification and dispersibility, helps to form a uniform foam structure, and improves the physical properties of the foam.
· Polyoxyethylene-polyoxypropylene block copolymer (Pluronic series): This type of non-ionic surfactant is composed of ethylene oxide and propylene oxide units, has good emulsification and wetting properties, and is suitable for a variety of polyurethane systems.
Silicone surfactants:
· Function: By reducing surface tension, improving the uniformity and stability of foam, it is widely used in the production of soft and hard polyurethane foam.
· Polydimethylsiloxane (PDMS): This is a linear silicone polymer with excellent surface activity and thermal stability, and is often used to regulate the fineness and stability of foam.
Anionic surfactants:
· Function: Dissociate negatively charged hydrophilic groups in aqueous solution, commonly used in polyurethane systems that need to enhance wettability and dispersibility.
· Sodium dodecyl sulfate (SDS): This is a common anionic surfactant with good detergency and foaming ability, but it is rarely used in polyurethane foam production.
Cationic surfactants:
· Function: Dissociate positively charged hydrophilic groups in aqueous solution, suitable for specific polyurethane application scenarios, providing antistatic and sterilization functions.
· Cetyltrimethylammonium bromide (CTAB): This cationic surfactant is mainly used in specific industrial applications and has limited application in polyurethane foam production.
Selecting the right surfactant type and composition is crucial to controlling the quality and performance of polyurethane foam. In practical applications, the most suitable surfactant should be selected according to the specific production process and product requirements to achieve the best foam performance.
