Chromium imine and amine complexes as homogeneous catalysts for the trimerisation and polymerisation of ethylene

Cr(III) complexes of tridendate imine and amine ligands with N, P, O, S donor atoms 1 and 2 have been prepared and tested as catalysts in the oligomerisation and polymerisation of ethylene giving excellent selectivity towards 1-hexene and polymerisation to polyethylene when activated with cocatalysts. X-ray structure analyses of the precatalysts 1a-c, 1i, and 2b are investigated. The metal-ligand binding in 1a and 1b is nearly the same, which leads to similar catalytic activities of these precatalysts.     

Ring‐Opening Metathesis Polymerization of Biomass‐Derived Levoglucosenol

The readily available cellulose‐derived bicyclic compound levoglucosenol was polymerized through ring‐opening metathesis polymerization (ROMP) to yield polylevoglucosenol as a novel type of biomass‐derived thermoplastic polyacetal, which, unlike polysaccharides, contains cyclic as well as linear segments in its main chain. High‐molar‐mass polyacetals with apparent weight‐average molar masses of up to 100 kg mol^?1 and dispersities of approximately 2 were produced despite the non‐living/controlled character of the polymerization due to irreversible deactivation or termination of the catalyst/active chain ends. The resulting highly functionalized polyacetals are glassy in bulk with a glass transition temperature of around 100 °C. In analogy to polysaccharides, polylevoglucosenol degrades slowly in an acidic environment.     

Transparent Omniphobic Coating with Glass‐Like Wear Resistance and Polymer‐Like Bendability

Transparent omniphobic or anti‐smudge coatings with glass‐like wear resistance and polymer‐like bendability have many potential applications but there are no reports of such materials. We Report herein a molecular composite possessing these properties. The composite is prepared via the photo‐initiated ring‐opening polymerization of the epoxide rings of glycidyloxypropyl polyhedral silsesquioxane (GPOSS). While the desired hardness is provided by the silica core, the flexibility is imparted by the glycidyloxypropyl network. Oil and water repellency is achieved without adversely affecting the other properties by incorporating a low‐surface‐tension liquid lubricant poly(dimethyl siloxane). On the final coating, various organic solvents and water readily and cleanly glide, while complex fluids, such as ink and paint facilely contract. These properties are retained after an initially flat coating sample is rolled into a U‐shape 500 times or is abraded with steel wool.     

Non‐natural Photoenzymatic Controlled Radical Polymerization Inspired by DNA Photolyase

Inspired by DNA photolyase, a non‐natural photoenzymatic catalysis of common flavoproteins is developed for controlled radical polymerization under irradiation of visible light. This photoenzymatic polymerization is highly efficient under mild conditions, applicable to various monomer families, suitable for both homogeneous and heterogeneous media, and can be externally modulated by switching light on and off. A unique combination of the natural enzymatic deoxygenation with the non‐natural photoenzymatic process enables an unprecedented oxygen‐tolerant, visible‐light‐controlled radical polymerization using a single enzyme to be developed. Visible light activation of non‐natural catalytic functions of the widely distributed flavoproteins is an exciting conceptual advance and may uncover a hitherto underexplored field of photoenzymatic catalysis.