Sequential Immobilization of Ansa-Hafnocene Complexes for Propene Polymerization

We report the immobilization of the ultrarigid ansa-hafnocene complexes [Me2Si(Ind*)2HfCl2] (Ind* = 7,(3\u27,5\u27-Di-tert-butylphenyl)-4-methoxy-2-methylindenyl) on silica as heteregeneous catalysts for propene polymerization. A sequential three-step synthesis on the siliceous surface led to pre-catalysts of the generalized structure SiO2-Si(Ind*)2HfCl2, which possess the silylene bridge of the substituted bis(indenyl) ligand directly attached to the surface. The immobilized pre-catalysts show very poor performance in the polymerization of propene, independent on the reaction conditions and the employed silica. Based on the results, we suggest that the close proximity of the catalyst to the surface combined with the steric congestion provoked by the ligand prevents a continuous polymerization, most likely due to a blockage of the catalytically active sites with growing polymer.<br /

Sustainable Polyesteramides and Copolyamides: Insights into the Copolymerization Behavior of Terpene‐Based Lactams

AbstractSustainable lactams, which are derived from terpenes, are used for the synthesis of different novel copolymers via ring‐opening polymerization. Different conditions are tested and the incorporation of the different monomers into the polymers is elucidated. This gives access to a variety of new polymer structures and their application range is thus remarkably extended

3D-Printed Metal–Organic Framework-Derived Composites for Enhanced Photocatalytic Hydrogen Generation

Direct ink writing technique is used to 3D print Ti-metal–organic framework (MOF) NH2-MIL-125 mixed with boehmite dispersal. Pt is also deposited onto 3D-printed monolith using atomic layer deposition (ALD) to offer additional catalytic sites. The Ti-MOF-derived powder sample and the pyrolyzed 3D-printed monolith samples are evaluated for photocatalytic H2 evolution under UV–vis light. As a proof of concept, herein, it is demonstrated that 3D-printed MOF-derived monolith photocatalysts show five times higher H2 evolution performance compared with TiO2/C powder sample due to better interaction between 3D-printed photocatalysts and the incident light. The high surface area, the formation of hierarchical macro- to nanopores, and the optimizable shape/size of the 3D-printed catalyst maximize the exposure of catalytic active sites to incident photons and increase their photocatalytic H2 evolution performance. In addition, the N-functionalized porous carbon from organic linker, and the uniformly distributed Pt/PtOx species deposited by ALD, provide cocatalytic active sites for photocatalytic reaction and further enhance photocatalytic activity 30% of 3D-printed monoliths. This work on the 3D-printed MOF-derived free-standing monoliths for photocatalytic application provides a readily available approach to further fabricate a variety of 3D-printed MOF-based and derived materials for different energy and environment applications.ChemE/O&O groe