Continuous Polymer Synthesis and Manufacturing of Polyurethane Elastomers Enabled by Automation

Connecting polymer synthesis and processing is an important challenge for streamlining the manufacturing of polymeric materials. In this work, the automated synthesis of acrylate-capped polyurethane oligomers is integrated with vat photopolymerization 3D printing. This strategy enabled the rapid manufacturing of a library of polyurethane-based elastomeric materials with differentiated thermal and mechanical properties. The automated semicontinuous batch synthesis approach proved enabling for resins with otherwise short shelf lives because of the intimate connection between synthesis, formulation, and processing. Structure–property studies demonstrated the ability to tune properties through systematic alteration of cross-link density and chemical composition

Ni/Photoredox-Catalyzed Enantioselective Cross-Electrophile Coupling of Styrene Oxides with Aryl Iodides

A Ni/photoredox-catalyzed enantioselective reductive coupling of styrene oxides and aryl iodides is reported. This reaction affords access to enantioenriched 2,2-diarylalcohols from racemic epoxides via a stereoconvergent mechanism. Multivariate linear regression (MVLR) analysis with 29 bioxazoline (BiOx) and biimidazoline (BiIm) ligands revealed that enantioselectivity correlates with electronic properties of the ligands, with more electron-donating ligands affording higher ee's. Experimental and computational mechanistic studies were conducted, lending support to the hypothesis that reductive elimination is enantiodetermining and the electronic character of the ligands influences the enantioselectivity by altering the position of the transition state structure along the reaction coordinate. This study demonstrates the benefits of utilizing statistical modeling as a platform for mechanistic understanding and provides new insight into an emerging class of chiral ligands for stereoconvergent Ni and Ni/photoredox cross-coupling

One Word: Polymers. The Development of Ruthenium-Based Catalysts for Ring Opening Metathesis Polymerization

The formation of carbon-carbon bonds is a challenging and important transformation in synthetic chemistry. In 2005 the Nobel Prize in Chemistry was awarded to Robert Grubbs for his work in the development of olefin metathesis, a reaction that forms two new carbon double bonds. One application of this reaction, ring opening metathesis polymerization (ROMP), has become especially entrenched in industry for its efficient use of inexpensive starting materials in an atom economical way. Our talk will focus on catalyst development for and applications of the ROMP reaction, demonstrating the utility of fundamental organometallic principles in rational catalyst design