Coexistence of Activated Monomer and Active Chain End Mechanisms in Cationic Copolymerization of Tetrahydrofuran with Ethylene Oxide

Abstract

Cationic copolymerization of tetrahydrofuran (THF) with ethylene oxide (EO) in the presence of diols proceeds with simultaneous participation of secondary and tertiary oxonium ions. This process comprises therefore some features of the activated monomer (AM) and the active chain end (ACE) mechanisms. The mechanism of copolymer formation was evaluated, and the kinetics of competing reactions involving both secondary and tertiary oxonium ions with nucleophiles present in the system was studied. The apparent rate constants were derived, allowing the estimation of the influence of copolymerization conditions on the composition and microstructure of copolymers.

Branched polyether with multiple primary hydroxyl groups: polymerization of 3-ethyl-3-hydroxymethyloxetane

“…It can also proceed simultaneously by both, like polymerization of G 1) and copolymerization of THF with ethylene oxide (THF exclusively by ACE, ethylene oxide by both) 9) . Polymerization by either of the polymerization mechanisms gives, on the basis of EOX, exactly the same repeating units (in Eq.…”

Mechanism of cyclics formation in the cationic copolymerization of tetrahydrofuran with ethylene oxide in the presence of diols

“…In the preceding paper, the kinetics of reactions involved in Scheme 1 was studied and corresponding apparent rate constants were determined 2) . It was assumed, that if reaction is carried out at very low instantaneous concentration of EO (slow addition of EO to the reaction mixture), reactions of the protonated EO and alkylated THF with EO may be neglected and the Scheme is reduced to four reactions (1 a -1 d).…”

Ring-Opening Polymerization—An Introductory Review

“…An alternative, third, mechanism proposed for the propagation of CROP is that the monomer is activated and carries the cationic center; the growth reaction is an electrophilic attack of the activated monomer on the chain end ( Figure 14). For some systems it has been shown that both mechanisms operate simultaneously [46]. There are at least three types of reactions [38], which compete with the propagation reaction during a CROP as shown in Figure 15.…”