100th Anniversary of Macromolecular Science Viewpoint: The Past, Present, and Future of Stereocontrolled Vinyl Polymerization

Abstract

The thermomechanical properties exhibited by synthetic macromolecules can be directly linked to their tacticity, or the relative stereochemistry of repeat units. The development of stereoselective coordination–insertion polymerization, for example, led to the discovery of isotactic polypropylene, now one of the most widely produced commodity plastics in the world. Widespread interest in controlling polymer tacticity has led to a variety of stereoselective polymerization methodologies; however, this area of polymer science has lagged behind when compared to the ability to control molecular weight, dispersity, and composition. Despite decades of advancements, many stereoregular vinyl polymers remain unknown, particularly those comprised of polar functionality or derived from renewable resources. This Viewpoint provides an overview of recent developments in stereocontrolled polymerization, with an emphasis on propagation mechanism, and highlights successes, limitations, and future challenges for continued innovation.

Recent Advances in Living Cationic Polymerization with Emerging Initiation/Controlling Systems

“…However, in comparison to methods developed to achieve targeted molecular weights and narrow dispersity, much less success has been received for stereocontrolled polymerization. [ 47 ] Because the growing chain end, which is a planar sp 2 ‐hybridized carbenium, is not stereochemically defined, tacticity control for a cationic polymerization process presents great challenge. Consequently, many properties of stereocontrolled PVEs, which represent a broad type of materials, remain elusive for many years.…”

“…Recently, while requirements on polymers keep increase due to the rapid improvements of many cutting‐edge areas, there are continuous needs to develop related synthetic methods. For instance, the spatiotemporally controlled polymerizations are highly interesting to surface fabrication, [ 40,41 ] 3D/4D printing and others; [ 9,42 ] metal‐free polymerizations are valuable for medical, [ 43,44 ] electrolyte, and electronic utilities; [ 43,45,46 ] stereoselective polymerizations show good potentials to provide high‐performance materials with easily available monomer; [ 47 ] and experimental procedures insensitive to atmosphere are very useful to nonexperts and many applications. [ 48–50 ]…”

Catalyst Type Effects on Structure/Property Relations of Polypropylene Random Copolymers

“…Although ZN type catalyst systems are dominating the commercial PO production, more than 80% of the overall PO manufacturing processes still using ZN catalysts, [65] single-center MC catalysts have attained great importance. [66,67] Metallorganic compounds have already been studied for more than 30 years as model compounds for ZN reactions. However, they were not applicable for commercial PO production because of their extremely low activity and poor stereo control.…”

Regio- and sequence-controlled conjugated topological oligomers and polymers via boronate-tag assisted solution-phase strategy

“…Natural biopolymers are chiral, and the precise monomer chirality could lead to the chemical conformation of the chain segments, which was primarily responsible for the spatial assembly of macromolecules 35 . Likewise, the stereochemistry in the nonnatural polymers was of significance, and the polymer with high tacticity had always been the goal of polymer synthesis 36 , 37 . The stereochemical architecture could also be precisely controlled in the sequence-controlled polymers, shown by some elegant reports in recent years (Fig.…”