| Abstract: | The microstructure of polybutadiene produced by anionic initiation in diethyl ether and tetrahydrofuran with counterions Li+, Na+ and K+ was determined by 1H- and 13C-NMR. Ionization suppressing salts were added in tetrahydrofuran to ensure that only the ion-pair reaction was studied. Results are compared with older published data. In general, the 1,4 content of the polymer increases with increasing counterion size but varies somewhat with solvent with a given counterion. The cis component of the 1,4 structures changes with temperature and counterion. It is suggested that this change reflects the proportion of cis and trans centers that carry the reaction. |
