Carbocationic Polymerization

Abstract

This article summarizes fundamental and general aspects of carbocationic polymerizations, with a historical overview and up‐to‐date references. Following general considerations, the basic elements of carbocationic polymerization, such as monomers, initiating systems, solvents, and temperature, are discussed. Special attention is given to carbocation stability, monomer nucleophilicity, and dynamic interactions. The section on the kinetics of carbocationic polymerization presents current understanding of the elementary reactions—initiation, propagation, termination and transfer reactions, and copolymerization. Controlled (living) carbocationic polymerization is discussed in a separate section. Finally, industrial carbocationic polymerizations are also reviewed.

Role of the Counteranion in the Stereospecific Living Cationic Polymerization of N-Vinylcarbazole and Vinyl Ethers: Mechanistic Investigation and Synthesis of Stereo-Designed Polymers

“…Cationic (co)­polymerization generates a variety of functional polymers, such as stimulus-responsive and degradable polymers, from various distinct polar and nonpolar monomers. − Notably, recent studies − have shown that stereoregular polymers generated via stereospecific cationic polymerization have conspicuous thermal and physical properties. However, stereoregulation in cationic polymerization is still a major challenge because of the difficulty in controlling the steric environment around the propagating sp 2 carbocations.…”

Rigidifying Cation-Tunable Nickel Catalysts Increases Activity and Polar Monomer Incorporation in Ethylene and Methyl Acrylate Copolymerization

“…As a control, reactions using just LiBAr F 4 and B­(C 6 F 5 ) 3 without a Ni catalyst and in the presence of ethylene/MA did not generate any polymers (Table , entry 7). These results suggest that the copolymers obtained were likely formed via coordination–insertion rather than cationic polymerization mechanisms . Finally, adding 5.0 equiv of LiBAr F 4 to the nickel catalyst led to a decrease in activity (e.g., entry 11 vs entry 12).…”

“…These results suggest that the copolymers obtained were likely formed via coordination−insertion 5 rather than cationic polymerization mechanisms. 39 Finally, adding 5.0 equiv of LiBAr F 4 to the nickel catalyst led to a decrease in activity (e.g., entry 11 vs entry 12). Because the optimal Ni3:Li + stoichiometry was determined to be 1:1, perhaps the presence of excess Li + causes formation of other multinuclear species that are not catalytically active.…”

Homogeneous and heterogeneous catalysts for the synthesis of highly reactive polyisobutylene: discovery, development and perspectives

“…Polyisobutylene and its copolymers represent the most important (co)polymers produced by the cationic polymerization at the industrial scale. [1] Three types of polyisobutylene (PIB), i.e., low (M n <5,000 Da), medium (M n ¼40,000-100,000 Da) and high (M n >100,000 Da) molecular weight are commercially available. Among them, the low molecular weight polyisobutylene (M n <5,000 Da) possessing vinylidene (exo-olefin) end group (so-called highly reactive polyisobutylene HR PIB, see Scheme 1) is occupied about 75% of total polyisobutylene market due to its use as a precursor for the preparation of ashless dispersants.…”