Synthesis and characterization of polypyrrole-coated poly(alkyl methacrylate) latex particles

Polypyrrole (PPy) has been deposited from aqueous solution onto two types of near-monodisperse poly(alkyl methacrylate) latexes and the resulting composite particles have been extensively characterized using SEM, DCP, XPS, FTIR, and electrical conductivity measurements. Poly(methyl methacrylate) (PMMA) latex is more difficult to coat than the polystyrene latexes previously reported by our group in that the deposited PPy overlayer is much less uniform. This difference is most likely related to the greater hydrophilicity of the PMMA surface. The poly(n-butyl methacrylate) (PBMA) latex has intermediate hydrophobic character, and, as a result, PPy overlayers on this substrate are somewhat more uniform than those obtained for PMMA particles. The PPy-coated PBMA latex is an interesting model system for understanding the behavior of PPy-coated film-forming latexes such as DSM's ConQuest (PPy-coated polyurethane particles). The lightly cross-linked outer shell of PPy hinders film formation significantly but conductive films can be obtained in the presence of coalescence aids such as N-methyl pyrrolidone. This cosolvent acts as a plasticizer for the PBMA latex and allows a reasonable degree of film formation at ambient temperature.