No abstract

The polymerization of tetrahydrofuran (THF) by means of various initiators has been found t o proceed through a stepwise addition mechanism in which the propagating chain continues to grow without considerable chain termination or chain transfer l-4). @he propagating species in this polymerization is believed to be cyclic trialkyloxonium ion (I). ITrialkyloxonium salts are strong alkylating agents and therefore can be used as initiator for the cationic polymerization of several cyclic monomers such as thiiranes 5), thietanes 576), and aziridines7). I n the present work the use of "living" poly-THF as initiator for the polymerization of different cyclic monomers has heen studied.A typical procedure was as follows : 0.5 ml of a 1.3 n solution of triethyloxonium tetrafluoroborate (TEFB) in dichloromethane was added to 2 ml of dry THF ([THF]/[TEFB] = 37). The mixture was stirred by means of a magnetical stirrer and kept at 20°C. After 15 min the reaction vessel was cooled to -3OoC, 8 ml of dry methylene chloride was added and the mixture was stirred until a homogeneous solution was obtained. Then, 2 ml of dimethylthietane (DMT) ([DMT]/[TEFB] = 16.6) was added and under continuous stirring the mixture was allowed to warm up to room temp. and kept at 20°C during 2 hrs. The solution was poured into 100 ml of methanol and the polymer was isolated by filtration and/or by evaporation of the solution.The following comonomers (Mz) have been used : propylene sulfide PS , thietane, 3.3-dimethylthietane (DMT), aziridine and N(2-phenylethy1)aziridine (NPEA). 289

No abstract