High-Throughput Approach in the Ring-Opening Polymerization of β‑Butyrolactone Enables Rapid Evaluation of Yttrium Salan Catalysts

Poly(3-hydroxybutyrate) (PHB) is a material produced naturally by bacteria but is also chemically accessible via ring-opening polymerization (ROP) of β-butyrolactone (β-BL). In ROP, catalyst design plays a key role in the production of PHB with different stereomicrostructures, i.e., syndiotactic, isotactic, or atactic PHB. In this work, we demonstrate a simple procedure for generating the catalysts in situ by conveniently combining a suitable yttrium precursor with the respective salan pro-ligand. This approach circumvents the elaborate isolation of the catalyst and enables the high-throughput screening of a library of yttrium salan catalysts for the ROP of β-BL. Electronic and steric influences of the ligand framework on stereoselectivity and activity of the catalyst as well as limitations could be determined, and structure–property relationships were established. Depending on the substitution pattern, these in situ-generated catalysts produced syndiotactic-enriched, isotactic-enriched, or atactic PHB with high activity

Ring-Opening Polymerization of a Bicyclic Lactone: Polyesters Derived from Norcamphor with Complete Chemical Recyclability

Chemical recycling of polymers is an elegant approach to achieve a circular economy and address the sustainability and end-of-life issues of plastics. Herein, we report the ring-opening polymerization of a bicyclic lactone that is easily accessible from norcamphor. High molecular weight polyesters (Mn up to 164 kg mol–1) are obtained using ZnEt2 as catalyst, while the polymerizability of the monomer is good even at high temperatures. More importantly, the polymers can be completely depolymerized under thermolysis conditions to selectively recover the pristine monomer. Thus, the monomer design strategy of using ring-fused/hybridized lactones enables an innovative monomer–polymer system that shows both high polymerizability and high depolymerizability

Ordered B‑Site Vacancies in an ABX₃ Formate Perovskite

We report the synthesis and structural characterization of the ABX3 perovskite frameworks [C­(NH2)3]­Mn1–x2+(Fe2x/33+,□x/3)­(HCOO)3 (□ = B-site vacancy). For large x, the vacancies order, lowering the crystal symmetry. This system establishes B-site vacancies as a new type of defect in formate perovskites, with important chemical, structural, and functional implications. Monte Carlo simulations driven by nearest-neighbor vacancy repulsions show checkerboard vacancy order to emerge for x > 0.6, in accord with experiment