Quantum-chemical study of the effect of butadiene interaction with anionic active sites on the polymer microstructure |
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Authors: | G.B. Erussalimsky V.A. Kormer |
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Affiliation: | S. V. Lebedev All-Union Synthetic Rubber Research Institute, Gapsalskaya 18, Leningrad 198035, U.S.S.R. |
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Abstract: | The electronic and geometric structure of the models for prereaction complexes of the anionic active sites for polymerization of butadiene have been calculated using a modified CNDO method: C4H4Li-cis-C4H6(I), C4H7Li-trans-C4H6(II), (C4H7Li)2-cis-C4H6(III) and (C4H7Li)2-trans-C4H6. The configuration of complexes I and II resulting from the total energy minimization points to the preferential C4H6 attack on the α-C atom of the monomeric active site (AS) leading to 1,4-units in polybutadiene. A more pronounced complexation effect observed with I as compared to II was taken into account when interpreting data on the preferential formation of cis-1,4-structure within macromolecules. The structure of models III and IV and also a decrease in the difference of the energy of interaction with C4H6 incorporated in these models, as compared to models I and II, indicate a decrease in the 1,4-cis-units content with increasing initiator concentration. Based on results of the present study, an evaluation was also made of the effect of the interaction between the living macromolecule aggregates and diene on the dissociation processes. |
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