Synthesis And Characterization Of EO/PO Random Copolyethers

Ethylene oxide(EO) and propylene oxide(PO) random copolymers are widely used as nonionic surfactants.The hydrophilic-lipophilic property of these copolymers can be tailored by varying their molecular weight or EO/PO mixture ratio. As a result, these copolymers have been found to have widespread industrial uses in detergency, dispersion stabilization, foaming, emulsification, lubrication, etc.. Much research has been focused on the synthesis and properties of block copolymers of ethylene oxide and propylene oxide using propylene glycol as an initiator, while research on random copolymers of this kind is relatively little.The presence of additives (i.e. electrolytes, non-electrolytes, organic solvents, homopolymers and ionic surfactants) has been found to exert a remarkable influence on the cloud point of EO/PO block copolymers. However, data on the effect of these additives influencing the cloud point of EO/PO random copolymers are rather scarce.In this article, the synthesis and characterization of random copolymers of ethylene oxide and propylene oxide is discussed. Through the research of the reaction conditions, the relation between structure and property of the polymer, a type of polyether that can -be used to prepare spinning finishes was expected to be synthesized. The effects of concentration of aqueous solutions, structure of random copolyethers, inorganic electrolytes, acids, alcohols, surfactants on the cloud point(CP) were discussed in detail. Some block copolymers of ethylene oxide and propylene oxide were synthesized, in order to compare the properties of their random counterparts. The main conclusions are showed as following:1. With the increase of the reaction temperature, the reaction speed is increased, and higher reaction temperature results in copolyethers with higher unsaturation level and darker color. With increase of catalyst concentration, the reaction is accelerated. With the increase of EO/PO mixture ratio, the reaction rate is increased, besides the molecular weights of copolyethers containing more ethylene oxide are closer totheoretical molecular weight.2. Ethylene oxide and propylene oxide random copolyethers were synthesized using KOH as catalyst and the monomer mixture are continuously feeded. The optimal condition for the synthesis of polyether is obtained:the concentration of KOH is 0. 25%, at 115°C, and pressure below 0.4MPa. The molecular weight distribution of the products that synthesized by this way is very narrow, and the products are colorless.3. If the boiling point of initiator is higher than 115°C the water should be get rid of at 80°C. However, if the boiling point of initiator is very low, some middle products should be synthesized with this initiator, then use the middle product as an initiator to synthesize final product.4. NMR and FTIR were used to characterize the structures of the copolyethers, and the relationships between structure and properties were analysed.5. The effects of concentration of aqueous solutions, structure of random copolyether, inorganic electrolytes, acids, alcohols, surfactants on the cloud point(CP) were studied. The results indicated that the CP of the random copolyether was decreased by electrolytes and increased slightly by acids. The effects of water soluble alcohols were different that of water insoluble alcohols. The CP was increased by the former, while decreased by the latter. The CP was increased by surfactants. With the rise of ethylene oxide in copolyether, the CP was raised. The CP was decreased with the enhancement of relative molecular weight. These laws will give some help for studying and applying of random copolyether.6. The thermal stability of block copolyether is higher than that of random copolyether, and the cloud point of this two kinds of polyethers is almost the same.7. The experiment results showed that the optimal end capped reaction condition is that the reaction time should be 8 hours, and the reaction temperature should be 120°C .The polyether/catalyst/end capped agent molar mixture ratio should be 1:2:1.5.