Methacrylic acid polymerization rate constants

Table 8.2 Rate constants " for template polymerization of methacrylic acid.

Figure 8.13. Template polymerization of methacrylic acid along with poly(N-vinylp5nrolidone). Termination rate constant as a function of [T o/[M]o.

It was recently shown12) that in radical polymerization the chain termination rate constant is observed to decrease with the introduction of a polyfunctional complex-ing agent into the system. An especially sharp decrease of the termination rate, up to the formation, under certain conditions, of living radical polymerization centers, was noted in the methyl methacrylate-orthophosphoric acid system. 

The synthesis of manganese acetate tetra-p-aminophenylporphyrinate (MnAc-TAPhP) chemically immobilized on different polymeric supports was carried out, and its catalytic activity during cholesterol oxidation by molecular oxygen was studied [107]. Soluble porphyrin-containing polymers were obtained by copolymerization of methacrylate or 4-vinylpyridine with the product of interaction of acrylic acid chloride with MnAcTAPhP. Cholesterol oxidation was performed in a 1 1 mixture of ethanol and chloroform. The effective rate constants, / eff, were determined from the initial rate of product formation. 

In a study of the polymerization of methacrylic acid in a solvent system consisting of water, dioxane, and ethanol, it was shown that at constant dielectric strength, the rate of polymerization increases with the concentration of water. On the other hand, at a constant concentration of water, the rate of polymerization was not significantly changed as the dielectric constant of the reaction medium was varied [39]. The ionic strength of the medium also seems to have, at best, only a slight influence on the rate of polymerization [38]. 

The polymerization of itaconic acid seems not to have been studied very extensively, although industrial applications in copolymer systems appear to be of considerable interest. In view of the work of A. Katchalsky and coworkers [38] on the effect of pH on the polymerization of acrylic acid and methacrylic acid, analogous research on pH effects on itaconic acid reactions has been carried out to a limited extent [95, 96]. Typically, with a persulfate initiator in an aqueous solution at 50°C, the monomer is converted to an extent of 85-90% to its homopolymer within 35-45 hr. In the pH range of 2.3-3.8, the rate of polymerization is constant. As the pH increases, the rate becomes progressively slower and stops completely at a pH of 9. Generally, the last 5-10% of the monomer seems to be difficult to convert to polymer. 

Karaputadze, T. M., Kurilova, A. I., Topchiev, D. A., Kabanov, V. A. (1972). Mechanism of the effect of pH and ionic strength on the chain propagation rate constant during radical polymerization of methacrylic and acrylic acids in aqueous solutions. Vysokomolekulyarnye Soedineniya, Seriya B Kratkie Soobshcheniya, 14, 323-325. 

Table 4 Rate constants of elementary processes for methacrylic acid template polymerization Temp. kp k,...

Recently Uniqema has introduced commercially a Surfmer under the trade name of Maxemul 5011. Maxemul is produced by esterification of an unsaturated fatty anhydride with a methoxy PEG such that the reactive group is close to the hydrophilic moiety [ 34 ]. Stable latexes with a solid content of 52% were produced in the seeded emulsion polymerization of film-forming methyl methacrylate/butyl acrylate/acrylic acid (3% Surfmer on monomers, constant monomer feeding rate over 4 h, potassium persulfate/sodium metabisulfate redox initiator). The latexes were stable to electrolytes but not to freeze-thaw. 

---