Ring-Opening Metathesis Polymerization in Emulsion

Abstract

Ring-opening metathesis polymerization (ROMP) of norbornene (NBE), catalyzed by water-soluble ruthenium alkylidenes 1, RuCl2(PCy2(C5H10NMe2Cl))2(CHPh), or 2, RuCl2(TPPTS)2(CHCO2Et) (TPPTS = tris(3-sulfonatophenyl)phosphine, sodium salt), has been carried out in emulsion. Polynorbornene latexes (PNBE) can be obtained in high yields, in the absence of floc, and with high solids, if Dowfax is used as surfactant. The nucleation mechanism of the polymerization has been found to be a continuous homogeneous nucleation. The resulting polymer particles are formed of aggregates of small primary particles, stabilized by the highly ionized chain ends. Typical particle sizes are ranging from 50 to 100 nm, even at higher solids. Less strained olefins, such as cyclooctene, COE, and 1,5-cyclooctadiene, COD, cannot be efficiently polymerized by catalysts 1 or 2. Nevertheless, these monomers are polymerized by a hydrophobic catalyst, 3, RuCl2(PCy3)2(CHPh). To form colloidal objects, the catalyst is dispersed into water through the use of a miniemulsion technique. The miniemulsion is then fed with monomer, and after polymerization, a latex is obtained. Monomer conversion is moderate, but a latex is generated in the absence of floc.

Nanoparticles by ROMP in Nonaqueous Emulsions

“…The first experiments on the synthesis of particles via ROMP were performed in 2001 with a relatively water stable catalyst in an aqueous emulsion process. [15] This approach resulted in particles with a broad size distribution and polymodality. In addition, it required a highly specialized catalyst.…”

Polymerization‐Induced Self‐Assembly (PISA) of 1,5‐Cyclooctadiene Using Ring Opening Metathesis Polymerization

“…ROMP is commonly conducted in solution in polar aprotic solvents since these do not coordinate with the transition metal‐based catalyst, but they do promote ligand dissociation . ROMP in aqueous dispersed systems (colloidal systems) has for many years been the subject of interest as it might represent a potential growing research area . ROMP in aqueous colloidal systems would offer reduced environmental impact since it would avoid the use of volatile organic compounds in the continuous phase, as well as having low viscosity, high weight fractions of polymer, and good heat transfer .…”

Aqueous Olefin Metathesis

“…Cyclooctadiene (COD) and cyclooctene (COE) can also be polymerized by this method. [25] Gnanou and co-workers synthesized norbornene latices by using 2 a in miniemulsion systems with SDS or poly(styrene-b-ethylene oxide) (PS-b-PEO) as the surfactant. In one approach, the catalyst was added to the miniemulsion of norbornene, either as a solid, as a solution in toluene, or as a dispersion in an aqueous medium.…”