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Zwitterionic catalysis is powerful in simultaneously activating electrophiles and nucleophiles in organic transformations; however, its potential in polymerizations remains untapped. Herein, a zwitterionic catalytic model for ring-opening polymerization (ROP) is introduced and a series quaternary ammonium carboxylate zwitterionic catalysts have been designed and evaluated in the ROPs of cyclic esters. Among the zwitterionic catalysts, L -carnitine, a commercially available and inexpensive natural product, showed the optimal catalytic performance. ROPs of L -lactide (L -LA), trimethylene carbonate, δ-valerolactone and ε-caprolactone were successful. PLLA was prepared with controlled molecular weight (1.4 to 21.2 kg mol−1) and narrow dispersion (Đ 1.02 to 1.21). The zwitterionic catalytic mechanism is proposed where quaternary ammonium and hydroxyl cooperatively activated the carbonyl of monomers, while the carboxylic anion activated the chain-end/initiator. NMR titrations validated the bifunctional activation mechanism. Organocatalysts of zwitterionic nature provide a new design tool for wider scope investigation of catalytic polymerizations. [ABSTRACT FROM AUTHOR]

In recent years, the development on sustainable and environmentally friendly materials has paid more and more attention. The polyglycolic acid (PGA), a biodegradable polymer, has emerged as a prime candidate due to its remarkable mechanical strength, rigidity, and gas barrier properties, which has been widely used in various practical applications. To gain insights into the PGA's behavior and properties under acidic and neutral and basic situations, a comprehensive theoretical and experimental study were performed to investigate PGA's hydrolysis behaviors in aqueous solutions. The density functional theory calculation was carried out to unveil the difference of PGA degradation mechanisms. The calculated results demonstrate that different degradation solutions play a significant impact on the degradation rates of PGA. Specifically, PGA degradation was the fastest in NaOH solution, followed by acidic solutions, with the slowest degradation observed in deionized water. Meanwhile, the experiments were performed and verified this preference of PGA degradation under basic condition. It was observed that the PGA experienced a greater degree of mass loss when exposed to basic condition, compared to those exposed to neutral and acidic environments. This work pointed out that the alkaline environment will facilitate the hydrolysis reaction of PGA. [ABSTRACT FROM AUTHOR]

This article reviewed the application progress in the additives in poly(glycolic acid) (PGA) processing, including antioxidants, chain extenders, anti-hydrolysis agents, and inorganic particles. [ABSTRACT FROM AUTHOR]