Living Ring-Opening Metathesis Polymerization in Aqueous Media Catalyzed by Well-Defined Ruthenium Carbene Complexes

Abstract

In aqueous media, two well-defined ruthenium carbene complexes [(Cy3P)2Cl2RuCHCHCPh2 (1) and (Cy3P)2Cl2RuCHPh (2), Cy = cyclohexyl] catalyzed living ring-opening metathesis polymerization (ROMP) of functionalized norbornenes and 7-oxanorbornenes. Monomers were dispersed in water using a cationic surfactant, and polymerization was initiated by injection of a catalyst solution to yield a polymer latex. The polymerization of hydrophilic 7-oxanorbornene monomer and a hydrophobic norbornene monomer displayed similar behavior in aqueous media, with the resultant polymers having lower molecular weights relative to polymerization in anhydrous organic solution on a similar time scale. The polydispersity indices (PDIs) of polymers prepared from the hydrophilic monomer using catalyst 1 in the presence of water (PDI = 1.20) were narrower than those obtained by solution polymerization (PDI = 2.11), while PDIs for polymers prepared using catalyst 2 remained low in both the presence of water and in anhydrous solution (P...