Preparation of polytetrahydrofuran monomethacrylate macromonomers by cationic ring-opening polymerization of tetrahydrofuran

Polytetrahydrofuran monomethacrylate (MA-PTHF) macromonomer was prepared by cationic ring-opening polymerization(CROP) of tetrahydrofuran (THF) using boron trifloride etherate (BF3 . OEt2) as initiator and epichlorohydrin (EC H) as promoter. Two kinds of transfer agents were used: methacrylic acid (r epresented as TA1), and a mixture of methacrylic acid and sodium methacryla te (represented as TA2). The effects of polymerization conditions on molecu lar weight and molecular weight distribution of macromonomers were studied in this article, when the composition of reactants was kept constant. Under the same conditions, the molecular weight of macromonomer using TA2 is low er than that using TA1, which indicates that TA2 is more active than TA1. T he molecular weight of MA-PTHF macromonomer varies with the polymerization time before transfer agents were added (T1), but molecular weight distribut ion remains constant. When T1 is limited in 30 min, the apparent number-ave rage molecular weight of MA-PTHF increases significantly with the increase of T1, and ranges from 5000 to 18,000. Hence, the molecular weight of MA-PT HF macromonomer can be controlled by varying T1. (C) 2000 John Wiley & Sons , Inc.