General organic compounds such as ethers, hydrocarbons, alcohols and phosphates, the spread coefficient is large, so the bubble breaking effect is very strong, but the bubble inhibition effect is very poor. Polyethers prepared by ring-opening polymerization of ethylene oxide and propylene oxide are excellent water-soluble non-ionic surfactants with typical structure of CnH2N + 10 O(EO) A (PO) BH. The poly (ethylene oxide) link in the molecule is hydrophilic and the poly (propylene oxide) link is hydrophobic. Polyether dissolves in water when the amount of ethylene oxide exceeds 25%. The index to characterize the solubility of polyethers is the turbidity point. Surfactants with different hydrophilic and oleophilic equilibrium values (HLB) can be prepared by adjusting the proportion of ethylene oxide and propylene oxide to obtain the desired surface activity. By adjusting the ratio of EO/PO and the relative molecular weight, the water solubility and oil solubility can be improved, the surface tension of the foaming liquid can be greatly reduced, and the foaming liquid has good anti-foaming and anti-foaming ability.
The biggest advantage of polyether defoaming agent is the strong foaming inhibition ability, so it is the leading defoaming agent used in the fermentation industry at present, but it has a fatal disadvantage that the breaking rate is low, once a lot of foam is produced, it can not be effectively extinguishing, but need to add a new amount of defoaming agent to slowly solve the problem.