A Catalyst Platform for Unique Cationic (Co)Polymerization in Aqueous Emulsion

Abstract

Sodium dodecyl benzene sulfonate (DBSNa) surfactants, with a polydisperse and hyperbranched structure, combined with different rare earth metal salts generate highly water-dispersible Lewis acid surfactant combined catalysts (LASCs). This platform of new complexes promotes fast, efficient cationic polymerization of industrially relevant monomers in direct emulsion at moderate temperature. The process described here does not require high shearing, long polymerization time, or large catalyst content. It allows the reproducible generation of high-molar-mass homopolymers of pMOS, styrene, and isoprene, as well as random or multiblock copolymers of the latter two, in a simple and straightforward one-pot reaction.

Carbocationic polymerization of isoprene using cumyl initiators: progress in understanding side reactions

“…In this study, no polymerization conditions could avoid the consumption of double bond, whereas the best polymerization conditions described so far for the conservation of the double bonds in the 5 cationic polymerization of isoprene are in aqueous medium. 7,22 Besides, the important double bond loss (30-60 %) observed in this work was always detected since the very beginning of the polymerization, involving most probably intramolecular cyclization reactions, as it was present even in conditions where 10 protons and interchain branching were absent. Indeed, sufficient proton trap was added to remove all free protons (coming from transfer reactions and water traces) and avoid gelation at 20°C.…”

High Molecular Weight Polystyrene Obtained by Cationic Emulsion Polymerization Catalyzed by Imidazolium‐Based Ionic Liquid

“…In addition, molecular weight increased when temperature was increased from 80 to 85 °C and from 85 to 90 °C, reaching an M w value above 1000 kDa (M n = 533 kDa).These molecular weights achieved with BMI.Fe 2 Cl 7 are higher than those reported for the cationic emulsion polymerization of styrene with other initiators. Vasilenko et al . reported molecular weights varying from 20 to 182 kDa (M n ) for the cationic emulsion polymerization of styrene and from 11 to 37 kDa (M n ) for the poly( p ‐methoxystyrene) with particle sizes close to 1 µm, both mediated by LASCs, using ytterbium as a salt.…”

“…This behavior lasted until the particles reached a certain diameter (Figure b) allowing the polymerization to occur in the particle core. Induction times have been reported in literature for cationic polymerization of styrene and p ‐methoxystyrene in aqueous emulsion using an in situ formed complex of a ytterbium‐based Lewis acid and a surfactant (LASCs). It is important to mention that this induction time was not observed in cationic styrene miniemulsion polymerizations conducted with the same IL, as reported by Alves et al., since in miniemulsion polymerizations droplet nucleation leads to the formation of bigger particles right from the beginning.…”

“…The group of Sawamoto was the first to show an efficient water‐tolerant catalyst based on lanthanides, mainly ytterbium, in the heterogeneous polymerization of p ‐metoxystyrene ( p ‐MOS) . Also using ytterbium, the research group of Ganachaud synthesized a complex known as Lewis acid surfactant combined catalysts (LASCs) for the polymerization of p ‐MOS and/or styrene in suspension, miniemulsion, and emulsion . While in their first works low molecular weights were achieved (M n of approximately 1 kDa), in the later works higher molecular weights were reached for poly( p ‐MOS) (M n of approximately 40 kDa), polystyrene (M n of approximately 180 kDa) …”

Characteristics and Mechanism of Styrene Cationic Polymerization in Aqueous Media Initiated by Cumyl Alcohol/B(C6F5)3

“…Due to the polymerizations proceeded at the droplet interface, synthesized polymers had limits on their molecular weight because of the “critical DP” effect . Subsequent works on a new initiating system named “Lewis acid surfactant combined catalyst” (LASC), which is made of lanthanide derivatives and surfactants, were investigated in the emulsion cationic polymerization of pMOS . These LASCs had the ability to shift the polymerization locus from the interface to the inside of monomer droplets, thereby increasing the molecular weight.…”