The reaction of 2‐[bis(2‐methoxy‐phenyl)phosphanyl]‐4‐methyl‐benzenesulfonic acid (a) and 2‐[bis(2′,6′‐dimethoxybiphenyl‐2‐yl)phosphanyl]benzenesulfonic acid (b) with dimethyl(N,N,N′,N′‐tetramethylethylenediamine)‐palladium(II) (PdMe2(TMEDA)) leads to the formation of TMEDA bridged palladium based polymerization catalysts (1a and 1b). Upon reaction with pyridine, two mononuclear catalysts are formed (2a and 2b). These catalysts are able to homopolymerize ethylene and also copolymerize ethylene with acrylates or with norbornenes. With ligand b, high molecular weight polymers are formed in high yields, but higher comonomer incorporations are obtained with ligand a.magnified image

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Ethylene was copolymerized with acrylates in solution and in emulsion using sulfonated arylphosphine Pd-based catalysts. The copolymerization of C 2 H 4 and methyl acrylate in toluene was slowed by the σ-coordination of the acrylate on Pd. The substitution of pyridine by itself was shown to proceed via an associative mechanism with activation parameters ΔH ‡ =16.8 kJ/mol and ΔS ‡ =-98 J mol -1 K -1 whereas the activation parameters for the substitution of pyridine by methyl acrylate were found to be ΔH ‡ =18.1 kJ/mol and ΔS ‡ =-87 J mol -1 K -1 . Using these Pd-based catalysts in an emulsion polymerization process, latexes of copolymers of ethylene with various acrylates having particle diameters ∼200 nm were obtained for the first time. Their solid contents did not exceed 5% because of the low activity of the catalyst resulting from the coordination of water and from the slow decomposition of the active site by water.

Zinc phosphate, and zinc molybdate nanoparticles were prepared from inverse microemulsions of inorganic salts stabilized by a mixture of nonionic and ionic surfactants in cyclohexane. The optimal ratios of surfactants to inorganic salts were found experimentally. The resulting nanoparticles were characterized by transmission electron microscopy, scanning electron microscopy, and X-ray diffraction. These nanoparticles were then mixed to epoxy formulations, which were applied to steel coupons. After accelerated aging, the electrochemical characteristics of the corrosion were analyzed by electrochemical impedance spectroscopy. The nanoparticles increase the corrosion resistance of the coating, indicating that the use of zinc phosphate and zinc molybdate nanoparticles offer a promising route for the mitigation of steel corrosion.