Poly-tetrahydrofuran (PTHF) with controllable molecular weight was synthesized in cationic ring-opening polymerization of tetrahydrofuran (THF) using phosphotungstic heteropolyacid (HPW)/epichlorohydrin (ECH) as initiator and ethylene glycol (EG) as chain transfer agent.Effects of various factors (polymerization temperature and time

content of ECH

HPW and EG) on the yield and Mn of PTHF product were comprehensively investigated based on a L16(45) orthogonal experimental design.Influence of chain transfer agent EG on THF polymerization was emphatically studied.Thermogravimetric analysis (TGA) was used to examine the weight loss curve of HPW from 25 ℃ to 400 ℃.Infrared spectra (IR)

proton nuclear magnetic resonance spectroscopy (1H-NMR) and gel permeation chromatography (GPC) were applied to characterize the terminal molecular structure

molecular weight and its distribution (MWD) of PTHF respectively.It was found that the HPW dried at 170 ℃ for 2 h exhibited the highest activity.The initiator and promotor have synergistic effects on THF polymerization.The addition of EG as chain transfer agent in the cationic ring-opening polymerization of THF can effectively control the chain propagation and depress the back-bitting reaction

which is attributed to the complication competition reaction between EG and THF.In the presence of EG

cyclic fraction obviously diminishes in the resulted PTHF product and the Mn of PTHF product decreases from 12000~23000 to 1100~1700.Also PTHFs MWD is significantly narrowed changing from bimodal distribution into single peak distribution.Moreover PTHFs yield increases from 50% to 80% because of its higher mass transfer efficiency.