Why Acetylenic Diol Surfactants Achieve Low Foam — Dynamic Surface Tension and Defoaming Mechanism
Acetylenic diols (Dynol) are a class of nonionic surfactants based on 2,5-dimethyl-3-hexyne-2,5-diol (TMDD). Unlike conventional ethoxylates, the acetylenic diol molecule contains a rigid alkyne bond, which makes it difficult to form stable micelles that trap gas in aqueous solution — the structural basis of its low-foam properties.
Dynamic Surface Tension and Foaming
Foam generation is directly related to the Marangoni effect of the liquid film. Ordinary surfactants adsorb quickly at the gas-liquid interface and form an elastic film with strong foam stabilization; acetylenic diols, due to their rigid molecules and moderate diffusion and adsorption rate to new interfaces, can rapidly reduce dynamic surface tension without forming an excessively strong elastic film.
Experimental Comparison
At the same concentration, the steady-state foam height of acetylenic diol solutions is significantly lower than that of fatty alcohol polyoxyethylene ethers, giving them excellent performance in foam-prone scenarios such as high-shear grinding and spray application.
Related Products
Toynol Superwet-320, FS-6502 and D-502 are all low-foam wetting agents based on the acetylenic diol structure.