Search for: All records

The development of robust methods for the synthesis of chemically recyclable polymers with tunable properties is necessary for the design of next-generation materials. Polyoxazolidinones (POxa), polymers with five-membered urethanes in their backbones, are an attractive target because they are strongly polar and have high thermal stability, but existing step-growth syntheses limit molar masses and methods to chemically recycle POxa to monomer are rare. Herein, we report the synthesis of high molar mass POxa via ring-opening metathesis polymerization of oxazolidinone-fused cyclooctenes. These novel polymers show <5% mass loss up to 382–411 °C and have tunable glass transition temperatures (14–48 °C) controlled by the side chain structure. We demonstrate facile chemical recycling to monomer and repolymerization despite moderately high monomer ring-strain energies, which we hypothesize are facilitated by the conformational restriction introduced by the fused oxazolidinone ring. This method represents the first chain growth synthesis of POxa and provides a versatile platform for the study and application of this emerging subclass of polyurethanes. 

We determine defining equations for the set of concise tensors of minimal border rank in Cm⊗Cm⊗Cm when m = 5 and the set of concise minimal border rank 1∗-generic tensors when m = 5, 6. We solve the classical problem in algebraic complexity theory of classifying minimal border rank tensors in the special case m = 5. Our proofs utilize two recent developments: the 111-equations defined by Buczy´nska–Buczy´nski and results of Jelisiejew–Šivic on the variety of commuting matrices. We introduce a new algebraic invariant of a concise tensor, its 111-algebra, and exploit it to give a strengthening of Friedland’s normal form for 1-degenerate tensors satisfying Strassen’s equations. We use the 111-algebra to characterize wild minimal border rank tensors and classify them in C5⊗C5⊗C5. 

Carbon dioxide-based polyoxazolidinones (POxa) are an emerging subclass of non-isocyanate polyurethanes for high temperature applications. Current POxa with rigid linkers suffer from limited solubility that hinders synthesis and characterization. Herein, we report the addition of alkyl and alkoxy solubilizing groups to rigid spirocyclic POxa and their poly(hydroxyoxazolidinone) (PHO) precursors. The modified polymers were soluble in up to six organic solvents, enabling characterization of key properties (e.g., molar mass and polymer structure) using solution-state methods. Dehydration of PHO to POxa changed solubility from highly polar to less polar solvents and improved thermal stability by 76–102 °C. The POxa had relatively high glass transition (85–119 °C) and melting (190–238 °C) temperatures tuned by solubilizing group structure. The improved understanding of factors affecting solubility, structure–property relationships, and degradation pathways gained in this study broadens the scope of soluble POxa and enables more rational design of this promising class of materials.