| Abstract
| - Statistical and block copolymerizations of tetrahydrofuran(T) and 7-oxabicyclo[2.2.1]heptane(B) (providing promesogenic units) have been studied.The structure of the active species and theirconcentration and stability were determined by the ion-trapping method,and on this basis the reactivitiesof T and B active species were estimated.B active species are about 10 times more reactive thanTones, reflecting the higher ring strain of B, due to thepresence of “two rings in one”. This highreactivityof B active species leads to the enhanced chain transfer tothe poly-T units and, therefore, eliminates thepossibility of preparing pure di- or triblock copolymer (bycopolymerization). The estimated ratio of therate constants of reaction between B active species andB monomer or T repeating unit (inhomosequences)is equal to 3 at typical copolymerization conditions. When,however, polymerization of B was startedfrom the active poly-T precursor, then multiblock copolymerswere prepared. For instance, a multiblockcopolymer of the average structure[(B)9.2(T)17.2]nwas prepared in CH3NO2 solution, fromwhich copolymerprecipitates.
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