Metallocene‐Catalyzed Polymerization in Nonaqueous Fluorous Emulsion

Abstract

A nonaqueous organic‐in‐fluorous emulsion applicable for polymerization using water‐sensitive catalysts is presented. With statistical biphasic copolymers based on poly(4‐hydroxystyrene) containing fluorinated and nonfluorinated alkyl side chains, emulsions of hydrocarbons dispersed in perfluorocarbons were stabilized. The addition of metallocenes, activated by methylalumoxane (MAO), enabled the polymerization of olefins inside this highly hydrophobic system. High molecular weight polyolefin nanoparticles ($\overline M _{\rm n}$ up to 450 000) of polyethylene and poly(propylene) were synthesized without supporting the catalyst and without reactor fouling. In this diffusion‐controlled process, the sizes of the particles were controlled by the reaction time and the ratio of the emulsifier to solvents.

Spherical Polyolefin Particles from Olefin Polymerization in the Confined Geometry of Porous Hollow Silica Particles

“…Figure f shows the profile of grown PE particles (60 min polymerization time) after a FIB cross‐section, revealing completely filled HSPs by poly(ethylene). To the best of our knowledge, spherical polyolefin particles in such a quality could only be obtained by using the confining geometry of nonaqueous emulsions . However, those polyolefin particles did not possess a comparably narrow and monomodal size distribution as reported here.…”

“…Additionally, the use of a supporting material is the only known way to run metallocene‐based polymerizations without a solvent in the gas phase. It is desirable to produce final polyolefin products with a particle size distribution as narrow as possible and with an almost perfect spherical shape, thereby generating a flowable powder and obviating the step of making pellets for subsequent processing steps . Commercially applied supports are usually composed of nanometer‐sized non­porous granulates (primary particles) of solid or hollow silica, as well as polymer‐based organic materials, compounded into micrometer‐sized agglomerates (secondary particles) with a wide range of sizes and shapes .…”

Poly(isobutylene) Nanoparticles via Cationic Polymerization in Nonaqueous Emulsions

“…In comparison, using the same initiator and monomer ratio as entry 5, the of a PIB sample prepared under homogenous conditions (entry 9) was ≈50% higher with a narrower molecular weight distribution (PDI = 1.2). A diffusion limitation of monomer was reported in the metallocene‐catalyzed polymerization of propylene in fluorous emulsion . Since monomer depletion is known to affect the polymerization of IB, these differences in molecular weights and PDIs were initially attributed to a similar diffusion limitation, which can result in a greater number of side reactions in the emulsion and termination of the propagating polymer.…”

Graphene as a Target for Polymer Synthesis

“…Some examples from the current cutting edge of polymer science illustrate these points. Metallocene-catalyzed polyolefin synthesis [22][23][24][25][26] has been developed to obtain an impressive microstructural precision, and chain-growth polymerization of activated olefins has become more and more controlled [27][28][29][30]. These techniques have furnished increasingly demanding polymer topologies such as block copolymers [31][32][33][34][35], star-polymers [36,37] or core-shell polymer nanoparticles [38][39][40][41][42][43].…”