The terpolymer of neodymium-catalyzed styrene, isoprene, and butadiene: efficient synthesis of integral rubber containing atactic styrene-styrene sequences and high Cis-1,4 polyconjugated olefins

The present study focuses on the terpolymer of styrene (St), isoprene (Ip), and butadiene (Bd) synthesized together in cyclohexane at 70°C with neodymium (Nd) compound, alkylaluminum, and chlorinating agent (Cl) rare earth cocatalyst system. The resultants possessed atactic St-St sequences and high cis-1,4 polyconjugated olefins in macromolecular chains besides controllable composition. The composition of the St-Ip-Bd terpolymers and molecular weight ([M.sub.w]), molecular weight distribution ([M.sub.w]/[M.sub.n]) were controlled through the adjustment of Nd compound, alkylalumium, monomers feed ratio (St/Ip/Bd), and [Nd]/[monomers]. With the inventory rating of St raised from 15% to 55%, the content of St in the terpolymers got increased from 2% to 15%. And the content of the Ip segments and Bd segments in the terpolymers increased from 33% to 56% and from 28% to 54%, respectively, with the proportion of Ip/Bd varied from 1/2 to 2/1. As the [Nd]/[monomers] varied from 1.0 x [10.sup.-3] to 5.0 x [10.sup.-4], the molecular weight increased from 1.3 x [10.sup.4] to 2.7 x [10.sup.4]. According to the proton nuclear magnetic resonance (1H-NMR) and 13C-NMR, it was proved that both microstructures of polybutadiene segments and polyisoprene segments were high cis-1,4-configuration. A single glass-transition temperature was observed in the differential scanning calorimetry curve.
INTRODUCTION Taking a world view of the current research in the field of synthetic rubber industry, one may easily find out that poly(conjugated-olefin) rubbers played an essential role in the [...]