三氟化硼引发四氢呋喃聚合的研究——以环氧氯丙烷为促进剂

<正> 四氢呋喃(THF)通过正离子开环聚合而制得的聚丁二醇(PTMG)是生产嵌段聚醚聚氨酯及嵌段聚醚聚酯弹性材料的重要原料。目前制备PTMG所采用的引发剂都是强酸型的,如高氯酸、氟磺酸或发烟硫酸等,对设备腐蚀严重。用酸性较弱的三氟化硼引发聚合在文献上也有一些研究报道,但尚难以采用,其主要困难在于实际应用的

POLYMERIZATION OF TETRAHYDROFURAN BY BORON TRIFLUORIDE INITIATOR——USING EPICHLOROHYDRIN AS THE PROMOTOR

The initiator efficiency in the tetrahydrofuran (THF) polymerization initiated by BF3 using epichlorohydrin (ECH) as the promotor is 2.5-6 times higher than that when ethylene oxi-de promotor was used. Five chain transfers, i.e. H₂SO₄, H₂S₂O₇, water, butylene glycol and acetic anhydride (Ac₂O) have been studied in this paper. With the addition of even a small amount of H₂SO₄ or H₂S₂O₇ to the reaction system the polymerization does not occur. In the presence of Ac₂O and 5 mol-% of the initiator the conversion reached 80% after 15min. of polymerization. In such a relatively rapid reaction the molecular weight ofthe product is little influenced by the conversion and feed amount of Ac₂O and therefore,can be controlled around 2000 by varying the amount of initiator charged. The end-groups of the product are mainly hydroxyls with some acetoxyls (lower than 15%). The total average functionality of the end-groups is close to 2.