Penultimate-unit effects in free-radical copolymerization

Abstract

The penultimate unit effects (PUEs) on the propagation, termination, and reversible addition‐fragmentation chain transfer (RAFT) processes in free radical copolymerization are discussed on the basis of recent publications. The propriety of the implicit and explicit PUE models in propagation and chain transfer processes is commented. The penultimate termination model with the geometric‐mean approximation and the related rate equation are highlighted.

Pulsed initiation polymerization as a means of obtaining propagation rate coefficients in free-radical polymerizations. II Review up to 2000

“…So in general from PLP experiments no inferences about trends in the product s 1 N s 2 can be made. [140] So far two terpolymerizations were investigated: Sty/ MMA/MA [50] and p-MOS/Sty/MMA. [92] In both cases the terminal model also failed to describe the data.…”

Kinetic study of radical polymerization. IV. Determination of reactivity ratio in copolymerization of styrene and itaconic acid by 1H‐NMR

“…The corresponding detail has been mentioned elsewhere. 31,32 These parameters are preferred to simple limits of precision because of simultaneous estimation of reactivity ratios. Hence, they should not be considered independent statistically.…”

Copolymerization of methyl methacrylate and butyl acrylate in the presence of a chain transfer agent

“…Furthermore, the average propagation rate constant coefficient (k p ) is also a function of the monomer reactivity ratios (r i ), monomer feed composition (f i ), individual propagation rate constant coefficients (k iii ), and the radical reactivity ratios (s i ) in the penultimate model: [32] k…”

“…As indicated above, the average propagation rate coefficient is a variable function whose value can be calculated using the penultimate effect theory proposed by Fukuda et al [32] Considering the reported values of the reactivity ratios of monomers and radicals for the MMA/ BA system [27] and the homopropagation rate coefficients for both methyl methacrylate [33] and butyl acrylate, [34,35] the average copolymerization propagation coefficients have been estimated disregarding the possible influence of the solvent.…”