Architecting Branch Structure in Terpolymer of CO2, Propylene Oxide and Phthalic Anhydride: An Enhancement in Thermal and Mechanical Performances

High-Molecular-Weight Biodegradable CO2/Propylene Oxide/Epichlorohydrin Terpolymers with Outstanding Gas Barrier Performance Synthesized Using an Organoboron Catalyst

As the sole commercial polycarbonate derived from CO2, poly(propylene carbonate) (PPC) is still hindered by poor thermal stability and a low glass transition temperature. Herein, first, the terpolymerization of CO2, propylene oxide (PO), and epichlorohydrin (ECH) to synthesize PPC-ECH terpolymers via one-pot and metal-free method using multinuclear organoboron catalysts is reported. The PPC-ECH terpolymers with well-rounded properties can be easily synthesized by adjusting reaction conditions, monomer ratios, catalyst types, and loading. The molecular weight of the PPC-ECH terpolymer can reach up to 59.4 kg mol-1, which is the highest known. Notably, the synthesized PPC-ECH exhibits outstanding barrier performance with oxygen permeability as low as 1.31 cm3 mm (m2 day)-1 and water vapor permeability as low as 0.016 g mm (m2 day)-1, significantly lower than those of pure PPC or other common packaging materials. Importantly, the introduction of a small amount of ECH not only preserves the biodegradability of polycarbonate but also markedly enhances its mechanical properties, glass transition temperature, thermal stability, and flame retardancy, offering promising prospects for application in packaging materials.

Polymer chain extenders induce significant toxicity through DAF-16 and SKN-1 pathways in Caenorhabditis elegans: A comparative analysis

Polymer chain extenders, commonly used in plastic production, have garnered increasing attention due to their potential environmental impacts. However, a comprehensive understanding of their ecological risks remains largely unknown. In this study, we employed the model organism Caenorhabditis elegans to investigate toxicological profiles of ten commonly-used chain extenders. Exposure to environmentally relevant concentrations of these chain extenders (ranging from 0.1 µg L-1 to 10 mg L-1) caused significant variations in toxicity. Lethality assays demonstrated the LC50 values ranged from 92.42 µg L-1 to 1553.65 mg L-1, indicating marked differences in acute toxicity. Sublethal exposures could inhibit nematodes' growth, shorten lifespan, and induce locomotor deficits, neuronal damage, and reproductive toxicity. Molecular analyses further elucidated the involvement of the DAF-16 and SKN-1 signaling pathways, as evidenced by upregulated expression of genes including ctl-1,2,3, sod-3, gcs-1, and gst-4. It implicates these pathways in mediating oxidative stress and toxicities induced by chain extenders. Particularly, hexamethylene diisocyanate and diallyl maleate exhibited markedly high toxicity among the chain extenders, as revealed through a comparative analysis of multiple endpoints. These findings demonstrate the potential ecotoxicological risks of polymer chain extenders, and suggest the need for more rigorous environmental safety assessments.