Kinetic Study of Radical Polymerization v. Determination of Reactivity Ratio in Copolymerization of Acrylonitrile and Itaconic Acid by¹H‐NMR

Abstract

Many reports exist in the literature about the application of 1 H and 13 C-NMR techniques to analyze the copolymer structure and composition and also determination of reactivity ratios. In this work, on-line 1 H-NMR spectroscopy has been applied to identify reactivity ratios of itaconic acid and acrylonitrile in the solution phase (DMSO as the solvent) and in the presence of AIBN as the radical initiator. All the peaks corresponding to the existing protons were assigned quietly. Therefore, the kinetics of the copolymerization reaction was investigated by studying the variation of integral of two characteristic peaks regarding each monomer. The obtained data were used to find the reactivity ratios of acrylonitrile and itaconic acid by linear least-squares methods such as Finemann-Ross, inverted Finemann-Ross, Mayo-Lewis, Kelen-Tudos, extended KelenTudos and Mao-Huglin. In addition, a non-linear least-square method (TidwellMortimer) was used at low conversions. Extended Kelen-Tudos and Mao-Huglin were applied to determine reactivity ratio values at high conversions as well.

Kinetic study of radical polymerization. VII. Investigation into the solution copolymerization of acrylonitrile and itaconic acid by real‐time 1H NMR spectroscopy

“…Individual monomer conversion was calculated by measuring the specific peak areas in the recorded spectra at different time intervals with respect to the first spectrum for each reaction mixture. 28 It is observable that area of the peaks in the aliphatic region ( Fig. 2), which shows the progress of copolymerization reaction, is growing up during the time.…”

“…During our investigation on kinetic studies of radical polymerization by several instrumental techniques in different media and conditions, [24][25][26][27][28] we were notified to the great potential of 1 H NMR spectroscopic technique, for these kinetic studies. Especially, on-line 1 H NMR spectroscopy gives us the most reliable data about the variation of conversion during the progress of reaction, with high accuracy.…”

“…The method of calculating f i (mole fraction of monomer i in the feed) and F i (mole fraction of monomer i in the copolymer chain) has been discussed in our previous article in detail. 27,28 The measured amounts of f 0 IA (mole fraction of IA in the initial feed) and F IA in these series of experiments are listed in Table I that have been used before for determination of reactivity ratios. 28 …”

“…27,28 The measured amounts of f 0 IA (mole fraction of IA in the initial feed) and F IA in these series of experiments are listed in Table I that have been used before for determination of reactivity ratios. 28 …”

“…28 A typical 1 H NMR spectrum of a sample during copolymerization reaction, which contains three components (monomers and copolymer), has been shown in Figure 1 and assignment of the peaks were performed according to the different types of protons. Also carboxylic acid proton appears as a broad peak above 10 ppm that has not been shown in Figure 1.…”