Methyl Vinyl Ether Maleic Acid Half Ester Copolymers as Dispersing Agents in Aqueous Flowable Formulations
SourceAqueous-based flowables have been studied using methyl vinyl ether monoalkyl maleate copolymers as anionic dispersing agents for pesticides such as atrazine, carbaryl, and chlorothalonil. These polymers have received EPA exemption for use in crop protection and on animals. The polymer types, which differ in the length of the alkyl ester side chain, or contain a carboxylic acid instead of the monoester with appropriate neutralization, were each paired with either nonionic or anionic surfactants, such as nonylphenol ethoxylate, tristyryl phenol ethoxylate, or N-methyl taurate, in water-based suspension concentrates. Physical-chemical data show these anionic polymers, new for agricultural applications, can be used to make stable dispersions with different pesticides under varying conditions of hard water. Prototype formulations and comparative stability data with commercial formulations are provided. A working model is used to explain the role of the polymers in stabilizing dispersions.