A ‘living’ polymer after cationic initiation

Stable organic cation salts: Ion pair equilibria and use in cationic polymerisation

“…When all monomer is consumed in polymerisation then the positive charge almost certainly resides on some small molecular species, not a polymer molecule. This is not necessarily so however, in the case of the polymerisation of tetrahydrofuran (THF), where the presence of "living" polymeric cations was demonstrated originally by Dreyfuss and Dreyfuss (50). Sangster and Worsfotd (27) have since been able to make direct conductance measurements, and evaluate Kd for the "living" oligomeric oxonium ion pair (BFT, counterion) derived from THF in methylene chloride at -0.5 ° C.…”

“…This situation has arisen partly as a result of the inherent lower reactivity of these monomers, and also from the fact that, in general their polymerisations are less susceptible to impurities and complicating side reactions. Especially advantageous in kinetic studies is the absence of monomer transfer processes and a situation approaching that found in "living" anionic vinyl polymerisations frequently prevails (50).…”

“…Perhaps the most studied monomer of this group has been tetrahydrofuran which has been shown to be capable of producing "living" polymers (50), and equally important, in the presence of stable salts such as Et30+BF4, to undergo a relatively fast and quantitative initiation reaction. The latter point was first proven conclusively by Saegusa and his co-workers (130,131) who estimated the concentration of active centres in polymerisations by terminating the reaction with sodium phenolate Na+OPh, and measuring the ofgtical density of the terminal phenoxide chromophore.…”

“Green” Atom Transfer Radical Polymerization: From Process Design to Preparation of Well-Defined Environmentally Friendly Polymeric Materials

“…The compounds of Cu I are generally unstable in aqueous media and tend to disproportionate (eq 15 and Scheme 5). For instance, the equilibrium constant of disproportionation of the free Cu + ion in water is as high as K disp ) 10 6 . 345 This value is very sensitive to the solvent nature.…”

Thermodynamics of Polymerization. III

“…However, equilibrium polymerization arising after cationic initiation of tetrahydrofuran has been reported [23]. @-Methylstyrene, at room temperature, is near its ceiling temperature, so that the depropagation reaction might be expected to be fast.…”