Stereoregular Polymers

Abstract

Control of structure of polymers is an important issue in polymer synthesis because it affects properties such as solubility, crystallinity, and thermal properties. The polymers having stereogenic centers on a main chain can be synthesized by vinyl polymerization of olefinic monomers or ring-opening polymerization of cyclic monomers. Control of trans-cis selectivity is also important for the polymers containing C C double bonds in the main chain. The progress of homogeneous metal complex catalysts for coordination and ring-opening polymerization enables tailor-made control of the stereoregularity of the polymers. In this article, general aspects of stereoregular polymers, especially the polymer of monosubstituted vinyl monomers, are described. Recent progress in stereospecific polymerization of propylene, α-olefins, and styrenes is also summarized. Propylene Polymerization.Isospecific Polymerization of Propylene by Ziegler-Natta Catalysts. In 1954, Natta found that TiCl 3 /Et 2 AlCl catalyst is effective for the synthesis of isotactic polypropylene (4,5). Ti(III) is the active species of the polymerization, whereas other Ti species are also included in the catalyst. Moreover, the stereospecific Ti(III) site as well as nonstereospecific Ti(III) site exists in the catalyst.

Rhodium-Catalyzed Hydrofunctionalization: Enantioselective Coupling of Indolines and 1,3-Dienes

“…Conjugated dienes are raw materials for polymerization and attractive building blocks for medicinal and natural product synthesis. 1,2 Inventing enantioselective strategies for functionalizing dienes is an important challenge that has inspired Pd-catalyzed hydroamination, 3 Co-catalyzed hydrovinylation, 4 and Ru-catalyzed hydrohydroxyalkylation. 5 To expand the power of hydrofunctionalization, we envisioned using Rh-hydride catalysis to couple 1,3dienes and nucleophiles (Figure 1).…”

Factors Affecting the Mechanism of 1,3-Butadiene Polymerization at Open Metal Sites in Co-MFU-4l

“…Polymerization of 1,3-butadiene to produce synthetic rubber is one of the most important transformations in the current rubber industry. 1,2 Among the three possible polybutadiene (PBD) products, 1,4-cis-PBD is of special interest to the tire industry due to its good low-temperature properties, high abrasion resistance, and high resilience to temperature changes. 3 However, 1,3-butadiene polymerization reactions featuring high 1,4-cis selectivity (>99%) have not yet been achieved with industrial heterogeneous catalysts.…”

Engineering of Syndiotactic and Isotactic Polystyrene-Based Copolymers via Stereoselective Catalytic Polymerization

“…The use of metal complexes, especially group 3 and 4 metallocenes and related derivatives, as (pre)catalysts is arguably the only way to access highly regular polymers, with controlled molecular weight and co-monomer distributions. The development of a new generation of polymerization catalysts is a powerful means to finely tune the microstructure of the polymer, and by extension, the macroscopic properties of the resulting materials [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 ].…”