Solution and emulsion polymerization with partially neutralized methacrylic acid

Abstract

SYNOPSISPolymerizations of partially neutralized methacrylic acid ( MAA) were performed in both solution and emulsion systems. Polymerizations of MAA in solution were performed at an overall degree of neutralization ranging between 0 and 1. The rate of polymerization of the acid is found to decrease as the degree of neutralization increases due to increased electrostatic repulsion of the dissociated acid species (anions). The degree of neutralization of the unreacted monomer increases as the conversion increases. A kinetic model based on a copolymerization mechanism is used to describe the reaction behavior. Partially neutralized methacrylic acid was also polymerized with styrene in a seeded emulsion system. The reaction rates of both the acid and styrene decrease as the overall degree of neutralization increases. A previously developed emulsion copolymerization kinetic model is extended to account for reaction of the anions and used to investigate the overall "terpolymerization" of the acid, anions, and styrene.

Seeded emulsion polymerization of styrene: influence of acrylic acid on the particle growth process

“…Carboxylated seed latexes were also used by Coen et al 30 to study the influence of pH on the emulsion polymerization of S. Poly(acrylic acid) as stabilizer played a crucial role in the mechanism of the polymerization, which is probably also the case in the work of Shoaf and Poehlein. 9,10 Our systems actually describe the carboxylation process of polystyrene latexes and in this context the limited effect of pH on the polymerization rate is plausible. n increases with the particle diameter which is in agreement with the emulsion-polymerization theory reported by Ugelstad et al 31 (see Fig.…”

Semi‐Continuous Emulsion Copolymerization of Styrene‐Butyl Acrylate with Methacrylic Acid: Box‐Behnken Design of Experiments

“…Since the MAA monomer is soluble in water and has a dissociation constant of pK a = 4.36, the partitioning of MAA between the aqueous phase and the particles depends on the pH of the reaction environment [12]. Increasing the pH led to higher concentrations of the dissociated form of the acid, and the quantity of MAA found in the organic phase decreased accordingly.…”

“…As a result, the increase in the hydrophilicity of the oligomeric radicals formed in the aqueous phase decreased the driving force for the radicals to penetrate into the hydrophobic particulate phase. Because of the MAA homopolymer at the surface of the polymer particles, the potential barrier for penetration of oligomeric radicals decreased the rate of polymerization at higher pH [12].…”

“…The influence of pH and the carboxylic acid monomer content on the polymerization rate and the amount of carboxylic acid groups incorporated into the final latex products are often of interest. Several important studies reported on the partitioning of carboxylic acid monomers between the aqueous and particulate phases [11,12], and the influence of pH on the distribution of acid monomers within the polymer particles, on their surface or in the aqueous phase of the latex [13,14]. The presence of MAA in St/BA emulsion polymerization processes has been shown to lead to significant changes in the mechanical properties of the final polymers [15,16].…”

Effect of Carboxylic Acid Monomer Type on Particle Nucleation and Growth in Emulsifier-free Emulsion Copolymerization of Styrene-Carboxylic Acid Monomer

“…polymerization rate per particle or equivalently average number of propagating radicals per particle is also affected by the presences of carboxylic acid monomers. 3,[5][6][7][8] Shoaf and Poehlein 7,8 developed a model that describes the kinetics of particle growth in seeded emulsion copolymerization of styrene with acrylic and methacrylic acids. These authors confirmed the influence of events taking place in the aqueous phase on the basic mechanisms operating in the particle growth stage.…”