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Catalyst-free and reversible step-growth Diels–Alder (DA) polymerization has found a wide range of applications in polymer synthesis and is a promising method to fabricate recyclable thermoplastics. The effectiveness of polymerization and de-polymerization relies on the chemical building blocks, often utilizing furan as the diene and maleimide as the dienophile. Compared to the traditional diene–dienophile or two-component approaches that requires perfect stoichiometry, cyclopentadi-ene (Cp) can serve a dual role via self-dimerization. This internally balanced platform offers a route to access high-molecular-weight polymers and a dynamic handle for polymer recycling, which remains unexplored. Herein, through the reactivity in-vestigation of different telechelic Cp derivatives, the uncontrolled cross-linking of Cp was addressed, revealing the first suc-cessful DA homopolymerization. To demonstrate the generality of our methodology, we synthesized and characterized six Cp homopolymers with backbones derived from common thermoplastics, such as polydimethylsiloxane, hydrogenated poly-butadiene, and ethylene phthalate. Among these materials, the hydrogenated polybutadiene-Cp analog can be thermally de-polymerized (Mn = 68 to 23 kDa) and re-polymerized to the parent polymer (Mn = 68 kDa) under solvent- and catalyst-free conditions. This process was repeated over three cycles without intermediate purification, confirming the efficient thermo-selective recyclability. The varied degradable properties of other four Cp-incorporated thermoplastics were also examined. Overall, this work provides a general methodology to access a new class of reversible homopolymers, potentially expanding the designs and construction of sustainable thermoplastics. 

Perovskite materials passivated by chiral ligands have recently shown unique chiroptical activity with promising optoelectronic applications. However, the ligands have been limited to chiral amines. Here, chiral phosphate molecules have been exploited to synthesize CsPbBr 3 nanoplatelets. The nanoplatelets showed a distinct circular dichroism signal and maintained their chiroptical properties after purification with anti-solvent. 

Misinformation about the coronavirus disease of 2019 (COVID-19) health crisis has been widespread on social media and caused various types of harms in society. While some researchers have investigated the way in which people perceive misinformation harm in crises, little research has systematically examined harms from health-related misinformation. In order to address this gap, we focus on non-comparative and comparative harm perceptions of the affected community in the COVID-19 pandemic context. We examine non-comparative harms (which component harms and contextual harms reflect) and comparative harms (which counter-contextual harms reflect) in order to understand harm perceptions. We also investigate how harm perception varies based on COVID-19 victimization experience. We used a professional survey company named Cint to collect data using a scenario-based survey with 343 participants. We extract various findings such as how contextual features shape perceived harms and reveal the scenarios in which COVID-19 victims perceive higher contextual harms but lower counter-contextual harms. We also examine how corrective actions of social media shape harm perceptions. 

A phosgene-free method to prepareN-carboxyanhydrides from amino acids and carbon dioxide has been developed. This method is mild enough to be used in the tandem synthesis of alkaloids tryptanthrin and phaitanthrin A.