Synthesis, ligand properties, and interfacial chemistry of metal carboxylate terminated oligomers of polyethylene

Abstract

Ethylene oligomers functionalized at their terminus with metal carboxylates were prepared. These oligomers were used to study ligation of metals by soluble metal carboxylates. They were also used to study chemistry at functionalized polyethylene surfaces. Using europium salts and fluorescence spectroscopy, we were able to show that an oligomeric carboxylic acid was a slightly better ligand for metal salts than octadecanoic acid. These studies quantified the ability of an oligomeric carboxylic acid to recover a metal and showed the potential utility for carboxylated ethylene oligomers as ligands for recoverable catalysts. We also used virgin polyethylene functionalized with copper carboxylate terminated ethylene oligomers to examine several aspects of chemistry at polymer interfaces. Kinetic plots for exchange reactions of diphenylthiocarbazone with copper at the polymer-solvent interface showed two distinct pseudo-first-order regions. The faster exchange involved a small amount of copper and occurred with a rate constant of 14.2 x 10^-5 s^-1. Region 2 involved more of the copper and the exchange rate constant was 1.86 x 10^-5 s^-1. These two regions merged into one when the polymer was annealed at [greater than or equal to] 100 °C. These reactions showed an Arrhenius temperature dependence in toluene and chloroform at -10 - 60 °C. We also observed that >75% of the total copper present in the polymer sample was extracted at 25 °C in toluene versus only 25% in chloroform.