The comppen model: A combined complex‐participation/penultimate effect model for free‐radical copolymerization

Abstract

SYNOPSISThe Comppen model for the mechanism of free-radical copolymerization has been developed to account for both penultimate effects and the participation of 1 : 1 electron donor-acceptor complexes during chain propagation. This was achieved by incorporating penultimate effects into the existing complex participation model of Cais, Farmer, Hill, and O'Donnell, using probability theory to derive new copolymer composition and sequence distribution equations that are solely functions of the reactivity ratios, the composition of the comonomer feed, and the equilibrium constant for 1 : 1 electron donor-acceptor complex formation. The model was applied to experimental data from styrene/maleic anhydride copolymers prepared in methyl ethyl ketone a t 50°C over a wide range of comonomer feed compositions, using nonlinear least-squares curve fitting techniques to determine best estimates of the reactivity ratios. Copolymer compositions and sequence distributions for copolymers in this comonomer system were then predicted using the Comppen model and compared to those determined experimentally via 13C-NMR spectroscopy.

Generalized (Ω) model of radical copolymerization Part 1. Combined Comppen model

“…As could be expected, the triad mole fractions calculated at O = 0.0 are the closest to the experimental ones, 1 con®rming again the supposition of the CA P mechanism. However, it is clear that the variability of the calculated values as a function of the O values is much higher than that of the monad copolymer composition.…”

“…This CD±P combination could be analysed by the classical probability approach, suggested by Hill et al 2,3 and used by Brown and Fujimori. 1 However, this could be achieved much more easily using the Markov chain apparatus, as in our previous work. 4 An important advantage of this approach is that it is free of limitations concerning the number of comonomers, complexes between them and terminal monomer units, in¯uencing the propagation radical reactivity.…”

“…This result is consistent with Brown and Fujimori's supposition for the realization of the CA P mechanism of the propagation reaction of the copolymerization discussed. 1 A peculiarity of the calculated m 0 values is their higher variation depending on O at smaller M 0 values. This cannot be explained by the possible increase of the comonomer complex participation in the formation of the copolymer molecule (P(c)).…”

“…The copolymerization convenient to this aim is that of maleic anhydride (0) and styrene (1) in methyl ethyl ketone (MEK) as a solvent at 50°C. 1 The monad and triad compositions of the produced copolymers were determined by 13 C NMR spectroscopy, 1 while the relative comonomer reactivities and complex formation constant were de®ned by the non-linear leastsquares curve-®tting techniques:…”

Hydrogen‐bonding interaction of an alternating maleic acid–vinyl acetate copolymer with poly(ethylene glycol), polyacrylamide and poly(N‐isopropylacrylamide): a comparative study

“…Moreover, the introduction of hydrophobic vinyl butyl ether groups into the structure of poly(diethylene glycol vinyl ether) intensifies the interpolymer interactions of copolymers with PAA in aqueous solutions owing to the strengthening of hydrophobic interactions 16. Maleic anhydride and maleic acid copolymers, soluble in aqueous media, have recently attracted major interest 17–19. Maleic acid copolymers could be an alternative for the polyacid in hydrogen‐bonding interpolymer complexes.…”