Capability of PN³-type Cobalt Complexes toward Selective (Co-)Polymerization of Myrcene, Butadiene, and Isoprene: Access to Biosourced Polymers

Abstract

In this manuscript, cobalt complexes Co1, Co2, and Co3 supported by PN3-type of ligand have been prepared, characterized, and applied in polymerization of myrcene (My), butadiene (Bd), and isoprene (Ip). The type of catalyst, cocatalyst, and temperature variation have little influence on polymer microstructure. We also have reported the preparation of novel isoprene–myrcene copolymers in the presence of complex Co1. Isoprene and myrcene are found to be randomly copolymerized at various monomer feeding, with typical myrcene incorporation of 7.6–57.6%. The copolymer has cis-1,4 microstructure of 69.4–73.4% and 79.4–83.4% for polyisoprene and polymyrcene segments, respectively, and T g = ca. −41.7 to 51.1 °C. The reactivity ratios obtained from the Fineman–Ross plot of r 1 = 0.74 and r 2 = 1.67 (r 1 = k mymy/k myip and r 2 = k ipip/k ipmy) indicate that isoprene has the privilege of getting into the macromolecules during the polymerization by this catalyst system.

Sustainable Myrcene-Based Elastomers via a Convenient Anionic Polymerization

“…Anionic polymerization promoted by i -Bu 3 Al/NaH was also applied to produce poly(M− co -I) (PMI). Copolymers of M and I were recently synthesized by lanthanum-based catalyst for coordinative chain transfer polymerization (generating high trans-1,4 microstructure for both M and I) [ 66 ], by cationic β-diimidosulfonate lutetium catalyst (obtaining isotactic 3,4-polymyrcene and polyisoprene) [ 67 ] and by PN3 type cobalt complexes [ 18 ] (obtaining predominantly 1,4- cis microstructure—up to 83% for myrcene).…”

“…Figure 4 shows the 13 C NMR spectra of PMI copolymers which have been produced starting from different initial M:I (mol/mol) ratios. All the main peaks were assigned based on examples in the literature [ 18 , 21 , 37 , 67 , 68 ]. Furthermore, PMI copolymers showed a monomodal and molecular weight distribution in the range 1.7–1.9.…”

“…Recently, homopolymerizations of M and its copolymerization with various comonomers, such as conjugated dienes [ 17 , 18 , 19 , 20 ], styrene (S) [ 21 , 22 , 23 , 24 ] and derivatives [ 25 ], ethylene and propylene [ 26 ], methacrylates [ 27 , 28 ], itaconic acid [ 29 ], and lactide [ 30 ] by coordinative mechanism [ 31 , 32 ], free [ 23 , 33 ] and controlled radical polymerizations [ 34 , 35 , 36 ], cationic [ 37 ] and anionic [ 38 , 39 , 40 ] polymerization methods have been reported. Very recently, a temperature-controlled one-pot anionic approach for the preparation of diblock copolymers consisting of PS and PM blocks has been described [ 41 ].…”

Introducing random bio-terpene segments to high cis-polybutadiene: making elastomeric materials more sustainable

“…The evaluated catalytic system provided a good stereoselectivity for both components in each series of copolymers, reporting up to 95, 71, and 86% of 1,4trans structure for PB, PMy, and PFa, respectively, and up to 92% of 1,2-structure for POc. Moreover, Yu et al, 20 Li et al, 21 and Liu et al 22,23 studied the copolymerization of My with isoprene employing different rare-earth-based catalytic systems, under varied reactions conditions. However, despite the numerous reports, little attention has been centered on randomly incorporating terpenes into PB with high cis-1,4 unit content, which shows superior mechanical performance, in terms of higher tensile strength and elongation at break, as well as improved fatigue and crack resistance.…”

Stereoregular Polymerization of Acyclic Terpenes

“…In 2019, the same authors synthesized new cobalt complexes (40)(41)(42), supported by pincer PN 3 ligands and activated by AlEt 2 Cl, for M polymerizations ([Al]/[Co] = 150-500, 1 h, 30-80 °C, toluene as solvent). [64] The microstructure of PMs was found from moderate to high cis-1,4 (76.7-98.4 %) with minor 3,4 units. By GPC, M n in the range 125-289 kg mol À 1 and narrow Ð (1.5-2.6) were observed.…”