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ABSTRACT:The preparation method for the monodisperse crystallizable polymer, poly(tetrahydrofuran), was studied over a wide range of molecular weights. Bulk polymerization of tetrahydrofuran (THF) was carried out by introducing THF monomer into a completely reacted trifluoroboron-THF---ethylene oxide catalyst-promoter system, with vigorous stirring. This initiation technique had no induction period. Both molecular weights and conversion increased linearly with reaction time. The molecular weight distribution evaluated by the sedimentation method as well as light scattering and osmometry was very sharp and Mwl JJiln was less than 1.01 even at the Mw=10 6 • When the polymerization is stopped at a low conversion (8 %), which is far from the equilibrium, the in-chain transfer reaction is negligible.KEY WORDS Poly(tetrahydrofuran) I Narrow Molecular WeightDistribution I Trifluoroboron-THF-Ethylene Oxide I CatalystPromoter I Impurity I Chain Transfer I Much progress has been made in the study of the physical properties of amorphous polymers since the preparation of monodisperse polystyrene by Szwarc. 1 It seems unnecessary to stress the importance of monodisperse crystallizable polymers in the study of polymer physics. A few monodisperse crystallizable polymers [poly(tetrahydrofuran), poly(ethylene oxide) have] been prepared.The purpose of this work is to study the preparation method for the monodisperse crystallizable polymer, poly(tetrahydrofuran) (PTHF), over a wide range of molecular weights. It was pointed oue·a that tetrahydrofuran (THF) can be polymerized on a living mechanism, by certain ring opening cationic initiators, and several papers 4 -10 have been published on the preparation of PTHF of narrow molecular weight distributions. However, these molecular weight distributions are not narrow enough and the molecular weight ranges covered are not wide enough. It is essential in the study of physical properties to have samples not only with sharp molecular weight distributions but also a wide molecular weight range.There are various cationic initiators presented in previous works: trifluoroboron (BF3)---ethylene Polymer

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