The main aim of this work is to obtain heterogeneous, zirconocene aluminohydride/methylaluminoxane (MAO) polymerization catalysts, without using inorganic carriers like silica. The syntheses of zirconocenium ion‐based clathrates, formed from aluminohydride zirconocene complexes activated with MAO, are reported here. Several different approaches were examined for the synthesis of these clathrate compositions; in one approach the catalyst (nBuCp2ZrH3AlH2/MAO) was first prepared in toluene solution, and the clathrate phase then generated by addition of silicone oil. An alternate approach involved reaction of silicone oil or another clathrate‐forming additive (e.g. KCl) with MAO to form a solidified clathrate, and then introducing the zirconocene aluminohydride complex (nBuCp2ZrH3AlH2). The clathrate catalysts were probed in the polymerization of ethylene in hydrocarbon slurry, without using additional co‐catalyst (MAO), or at very low concentrations of modified MAO (MMAO 7, 13 wt‐% in iso‐octane). The catalytic activities of the solid clathrate catalysts were compared as well as the morphology and properties of the polyethylene synthesized in slurry.

In this work, poly(alkylmethacrylates) based on poly(n-alkyl methacrylate) s (PnAMAs), that is, poly(hexyl methacrylate) (PHMA), poly(lauryl methacrylate) (PLMA), and poly(stearyl methacrylate) (PSMA), with similar molar masses (M n ), are synthesized via reversible addition-fragmentation chain transfer technique using a high-throughput approach. Analyses by dynamic light scattering (DLS) of PnAMAs in nonpolar solvents show the presence of nanoparticles distributions (unimers or single chains). Interactions of methylaluminoxane (MAO) and MAO/metallocene compounds withPnAMA nanoparticles, lead to self-assembled micellar-like structures useful as "nanoreactors" for coordination polymerizations of ethylene. The inverse micellarlike structures of the three kinds of polymethacrylates, formed in the presence of MAO are confirmed by DLS experiments and by transmission electron microscopy using energy dispersive spectrometry analyzer, in dyed PnAMAs/ MAO samples. The encapsulation of the metallocene catalyst into the PSMA/ MAO nanoparticles reveals stable catalytic systems that have a clear effect on the morphology of the polyethylenes synthesized through this method.

Front Cover: In article number 1900259 by Carlos Guerrero‐Sánchez, Odilia Pérez‐Camacho, and co‐workers, self‐assembled structures based on poly(alkylmethacrylates) (PnAMAs) and methylaluminoxane (MAO) are used to stabilize metallocene catalytic systems and to control the morphology of high density polyethylene (HDPE) in ethylene polymerizations. Characterizations by dynamic light scattering (DLS), transmission electron microscopy (TEM), and bulk density of HDPE, confirmed that poly(stearylmethacrylate/methylaluminoxane) (PSMA/MAO) can stabilize metallocene systems leading to “nanoreactors” for ethylene polymerization in heterogeneous phase using low concentrations of activator.