Experimental and Modeling Investigation of Radical Homopolymerization of 2‐(Methacryloyloxyethyl) Trimethylammonium Chloride in Aqueous Solution

Abstract

The radical homopolymerization kinetics of 2‐(methacryloyloxyethyl) trimethylammonium chloride (TMAEMC) in aqueous solution is investigated across a wide range of initial monomer contents (5–35 wt%), ionic strengths, and pH levels using an in‐situ NMR technique to track monomer consumption over the complete conversion range. Molar mass distributions (MMD) of the final homopolymers are also examined, with additional batch and semi‐batch experiments conducted in a stirred vessel. The rates of monomer conversion and polymer MMDs are dependent on initial monomer content but almost entirely independent of pH and the presence of salts, with some acceleration of rate observed for low monomer levels at very high salt concentration. To aid with the interpretation of these results, the conductivity and counterion activity of monomer and polymer mixtures are measured to determine the extent of electrostatic interactions at various levels of conversion. These results are combined with recently reported measurements of TMAEMC homopropagation kinetics to develop a TMAEMC homopolymerization model that captures the systematic decrease in rates of monomer conversion observed with increased initial monomer content during batch polymerization as well as provides a good representation of semi‐batch polymerization.

PLP-SEC Investigation of the Influence of Electrostatic Interactions on the Radical Propagation Rate Coefficients of Cationic Monomers TMAEMC and MAPTAC

“…Figure 11b also indicates that the variation in k p /⟨k t ⟩ 0.5 with conversion is relatively small for all initial monomer concentrations, in agreement with the previous study of TMAEMC kinetics by Drawe et al 28 Furthermore, it was found that solution pH, when both lowered (to 2.5) and increased (to 7.5) from the natural pH ∼ 4, had a negligible influence on TMAEMC batch polymerization kinetics. 31 Herein, we compare these TMAEMC results with conversion profiles obtained for MAPTAC using the same in situ NMR technique, also at 50 °C, and covering the same range of initial monomer contents, c M,0 , between 5 and 35 wt %. However, here, the initiator concentration was increased to 0.80 wt % V-50 because of the reduced MAPTAC k p value relative to TMAEMC.…”

“…The k p values show the independence on pH that is expected for these permanently ionized cationic monomers, for which the rate of polymerization has also been shown to be independent of pH. 31 The averaged k p values from these experiments within the pH ranges examined are 2080 ± 120 and 1160 ± 50 L• mol −1 •s −1 for TMAEMC and MAPTAC, respectively.…”

“…All in situ NMR experiments with MAPTAC were carried out in deuterium oxide (D 2 O, 99.9%, Cambridge Isotope Laboratories, Inc.), following the procedures described in a recent study of TMAEMC batch homopolymerization. 31 Hydrochloric acid (HCl, reagent, ACS−PUR, Fisherbrand) was used to adjust solution pH. The peak assignments used to calculate conversion from the NMR spectrum are shown in Figure S4.…”

“…This study enabled us to recognize the role of counterions (i.e., anions) in the propagation kinetics for these two monomers. The k p values reported in this work have already been used for modeling of TMAEMC , and MAPTAC homopolymerization and copolymerization with acrylic acid. In this work, we also compare the batch polymerization behavior between MAPTAC and TMAEMC monomers.…”

Kinetics of poly(3‐methacryloylamido propyl trimethyl ammonium chloride) initiated by different initiators

“…[3][4][5][6] The method of aqueous solution polymerization is widely used to prepare the polymers due to the advantages of simple technologies, low cost, safe operation, no solvent recovery, and so on. [7][8][9][10] There are few reports on the preparation of PMAPTAC homopolymers by aqueous polymerization method, 11,12 but there is a lack of relevant reports on the homopolymerization kinetics of PMAPTAC. There is only one literature report on the kinetics of research on the copolymerization of acrylamide (AM) and methacrylamidopropyl trimethyl ammonium chloride (MAPTAC).…”