Stereo-polymerization of 1,3-Butadiene by Cobalt Catalysts in the Presence of External Donor: Access to 1,2-Syndiotactic Polybutadiene with Tunable Properties

Abstract

Disulfide carbon (CS 2 ) and triphenyl phosphine (TPP) were tested as donors for cobalt (Co1, Co2, and Co3)catalyzed 1,2-syndiotactic polymerization of butadiene. With CS 2 , a 1,2-selectivity of 96.8% and syndiotacticity (rr) up to 97% were achieved by Co1−Co3/Al i Bu 3 /CS 2 , yielding highly crystallized polybutadiene resin. Variations on polymerization temperature (0−80 °C), catalyst loading, and polymerization time did not significantly affect the 1,2-incorporation and syndiotactic conformation of the resulting polymers, highlighting the excellent 1,2-stereoselectivity of active species stabilized by CS 2 . With external donor TPP, the formed Co1−Co3/MAO/TPP have regioselectivities of 65.2−89.2% and syndiotacticities of 32.1−65.5%. Thus, an array of polybutadienes differing in chemoenchainment and 1,2-stereoenchainment is accessible with the present cobalt catalysts in combination with different donors. AFM measurements were performed to distinguish the morphology of two types of 1,2-syn-polybutadiene. Elucidation on the plausible role of CS 2 and TPP in the stereoselective polymerization reaction was also made.

Synthesis and properties of syndiotactic 1,2‐polybutadiene catalyzed by iron catalyst with phosphate as additive

“…The characteristic 1,2 regio‐selectivity can be interpreted assuming a cis ‐ η 4 ‐coordination for the monomer and an anti ‐ η 3 bond between the growing polymer chain and the iron ionic, as proposed by Natta et al and Ricci et al 2,42 It is conceivable that primary 1,2 regiochemistry of butadiene polymerization occurs by reaction of the new monomer to C3 of the last‐inserted allylic units 46,47 . The stereospecificity strongly depends reciprocal orientation of coordinated monomers and the allyic terminal, differing from non‐metallocene catalyst for propene polymerization 21,22 .…”

“…We have made great contribution to 1,2 stereoselective polymerization by iron catalyst with the aid of dialkyl(aromatic) hydrogen phosphites 37–39 and triarylphoshate as additive 40–42 . The phosphoryl moiety played significant role in stabilizing the active species and inducing 1,2 syndiotactic stereospecificity.…”

Isoprene polymerization catalyzed by iron (II) and cobalt(II) complexes carrying 2,6‐bis(1H′‐allylbenzimidazolyl)pyridyl ligand

“…Carbon disulfide (CS 2 ) has been proved to be an efficient stereo‐regulator in cobalt‐catalyzed catalyzed polymerization of butadiene 35–37 . It is interesting to find that catalytic performances are greatly influenced by adding of CS 2 as well.…”

“…Carbon disulfide (CS 2 ) has been proved to be an efficient stereo-regulator in cobalt-catalyzed catalyzed polymerization of butadiene. [35][36][37] It is interesting to find that catalytic performances are greatly influenced by adding of CS 2 as well. The first set of reactions was performed by increasing progressively the amount of CS 2 in the presence of a fixed amount of MAO (entries 5-7, Table 2).…”

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

“…[10][11][12] Metallocene catalysts have occupied a certain position in the polybutadiene market, 13,14 but in order to better control the polymer stereoregularity, people still devote a lot of effort to exploring Ziegler-Natta catalysts, including iron, cobalt, chromium, etc. [15][16][17] The Mo-based polybutadiene catalytic system has stable 1,2-stereoselectivity. It has been confirmed that changing the type and dosage of ligands or co-catalysts in the catalytic system fails to significantly change the polymer microstructure.…”