Tuning the Reactivity of Cyclopropenes from Living Ring‐Opening Metathesis Polymerization (ROMP) to Single‐Addition and Alternating ROMP

Ring‐opening metathesis polymerization (ROMP) has become one of the most important living polymerizations. Cyclopropenes (CPEs) remain underexplored for ROMP. Described here is that the simple swap of 1‐methyl to 1‐phenyl on 1‐(benzoyloxymethyl)CPEs elicited strikingly different modes of reactivity, switching from living polymerization to either selective single‐addition or living alternating ROMP. The distinct reactivity stems from differences in steric repulsions at the Ru alkylidene after CPE ring opening. Possible olefin or oxygen chelation from ring‐opened CPE substituents was also observed to significantly affect the rate of propagation. These results demonstrate the versatility of CPEs as a new class of monomers for ROMP, provide mechanistic insights for designing new monomers with rare single‐addition reactivity, and generate a new functionalizable alternating copolymer scaffold with controlled molecular weight and low dispersity.     

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.