Complete end-capping during the copolymerization of trioxane and ethylene o
xide in the bulk polymerization state using boron trifluoride dibutyl ether
as the initiator and methylal as the chain transfer agent was accomplished
. By using highly purified trioxane as the starting material and by complet
ely deactivating the catalyst residue, an almost completely end-capped poly
mer (degree of stability was over 99.5%) was obtained.