Synthesis of Double Alkyl EO/PO Random Copolyethers with KOH Catalyst

Abstract

Ethylene oxide (EO) and propylene oxide (PO) random copolymer was synthesized with 1,2-propanediol as initiator, then the end-capping process was carried out by adding various alkyl halides and potassium hydroxide (KOH) to produce the double alkyl EO/PO random copolyethers. The factors effecting alkyl-capping rate were discussed. The results showed that when the molar ratio of hydroxyl group/KOH/1-bromobutane was 1/1.9/1.9, reacting time 6.5 hr and reacting temperature 50°C, the alkyl-capping rate could reach over 80%. The end-capping rate would also increase with the increasing content of ethylene oxide in the random polyether, and the end-capping rate of the EO/PO/EO block-polyether was high than that of the random polyether with same molecular weight. Instead of 1-bromobutane, ethyl bromide promised a higher whereas chloralkane gave a lower end-capping rate respectively.