Synthesis and characterization of the hydroxyl-terminated block copolyether of PPO-PTHF-PPO by macroinitiator method

The new hydroxyl-terminated copolyether (PPO-PTHF-PPO) was synthesized by epoxy propane cationic ring-opening polymerization and polypropylene glycol chains connected with the two terminals of polytetrahydrofuran glycol (PTMG) with PTMG as macroinitiator and boron-trifuoride ethylether complex (BF₃·OEt₂) as the catalyst. The copolyether was purified by water, and molecular weight by size-exclusion chromatography (GPC). The macromolecular structure of copolyether was also characterized by IR and ¹H-NMR, ¹³C-NMR. The effect of reaction conditions on the polymerization yield and molecular weight of the product was studied, the results show that the reaction temperature at 0 °C, reaction time for 5h, the catalyst for 3% of propylene oxide molar amount are most satisfactory, and the molecular weight of copolyether can be adjusted by the dosage of macroinitiator.