Controlling external diphenylcyclohexylphosphine feeding to achieve cis-1,4-syn-1,2 sequence controlled polybutadienes via cobalt catalyzed 1,3-butadiene polymerization

Dienes Polymerization: Where We Are and What Lies Ahead

“…Catalytic systems completely similar to the one described above have been subsequently reported in the literature. 273,275 Stereoblock polybutadienes have also been obtained with catalytic systems based on neodymium 269 and transition metals (Cr, Fe, Co). 266 Stereoblock polymers have also been prepared in the case of isoprene, using catalytic systems based on cobalt 270,271,274 and lanthanides (Y, Nd).…”

“…The recent discovery and introduction of new catalytic systems having not only high catalytic activity and selectivity but also some living features and the ability to change their selectivity during polymerization while maintaining their living nature can be extremely useful for this purpose. The strategies adopted to modify the selectivity during the polymerization runs are of different types, ranging from adding a specific ligand to changing the cocatalyst (i.e., different type of aluminum alkyl) and from increasing the Al/Mt molar ratio to modifying the polymerization temperature. ,,− …”

Balance of the steric hindrance and solubility of alkoxy ligands for ultrahigh-activity molybdenum-based butadiene coordination polymerization

“…The 1,2-content of polybutadiene and its syndiotacticity were determined by following the reported methods in the literature. 34,35 X-ray single crystal diffraction was conducted using a Bruker Smart-Apex-II single crystal diffractometer with a testing temperature of 23 °C. The single crystal structure was analyzed using the SHELXTL 97 program.…”

Intra-Ligand H···F Interactions: Non-negligible Forces for Enhancing Thermostability of Cobalt Complexes in 1,3-Butadiene Polymerization

“…The ligand structure plays a pivotal role in governing the catalytic behaviors, including reactivity, selectivity, and so forth, of the organometallic complexes and the molecular parameters, including molecular weight, polydispersity, and so forth, of the resultant polymer products. − This has been especially prominent for α-diimine late-transition meal complex-mediated olefin polymerizations, wherein the catalytic performances and polymer properties can be regulated in a large scope through varying the ligand substituents. − Generally, steric and electronic modifications of the ligands are the most two common strategies that had been employed during the past investigations, from which a basic structure–reactivity relationship has been elucidated. Besides these, scientists are also trying to tap alternative strategies to better modulate the catalytic performances and simultaneously avoid the exhausted research studies that are usually required for steric and electronic tunings .…”