The present study utilized chitosan obtained from crab shell and transition metal salts as precursors to synthesize chitosan-metal coordination biopolymers of Mn(II), Fe(III), Co(II) and Ni(II) [i.e. Chit-Mn(II), Chit-Fe(III), Chit-Co(II) and Chit-NI(II) respectively]. The synthesized coordination biopolymers have been characterized using different instrumental techniques such as spectroscopic (UV–visible, FT-IR, XRD, EDS, and ICP-OES), thermal analysis (TGA and DTA), surface analysis (SEM), and hydrogen-temperature programmed reduction (H₂-TPR) analysis. Spectroscopic studies confirmed the successful incorporation of the metals into the biopolymer matrix. Thermal analysis and H₂-TPR revealed the reducibility of the Chit-Fe(III) at 120 ℃. While Chit-Fe(III) and Chit-Ni(II) were inactive, Chit-Co(II) and Chit-Mn(II) were found to be active towards vinyl acetate polymerization in the presence of aqueous Na₂SO₃. Furthermore, the polyvinyl acetate (PVAc) produced from Chit-Co(II) compared perfectly with a commercial PVAc and was in higher yield than PVAc produced from Chit-Mn(II). The polymerization has been shown to proceed via surface-initiated atom transfer radical polymerization (SI-ATRP), and the viscosity average molecular weight of PVAc produced has been measured as 25, 078. The density functional theory approach has been used to ascertain the coordination orientation of the Chit-Co(II) and explain its high efficiency towards vinyl acetate polymerization. The catalyst reusability test revealed an insignificant loss of activity for the Chit-Co(II) after seven cycles of polymerization. Kinetics and thermodynamic studies show that the vinyl acetate polymerization is an endothermic process and proceed at ambient temperature. The result of this work also suggests an investigation of chitosan-metal coordination biopolymer via low-ppm ATRP approach for possible biomedical application.

本研究利用从蟹壳中提取的壳聚糖和过渡金属盐作为前体合成 Mn(II)、Fe(III)、Co(II) 和 Ni(II) 的壳聚糖-金属配位生物聚合物 [即 Chit-Mn(II) , Chit-Fe(III), Chit-Co(II) 和 Chit-NI(II)]。合成的配位生物聚合物已使用不同的仪器技术进行表征，例如光谱（UV-可见光、FT-IR、XRD、EDS 和 ICP-OES）、热分析（TGA 和 DTA）、表面分析（SEM）和氢-程序升温还原（H ₂ -TPR）分析。光谱研究证实了金属成功地结合到生物聚合物基质中。热分析和 H ₂-TPR 揭示了 Chit-Fe(III) 在 120 ℃ 的还原性。虽然 Chit-Fe(III) 和 Chit-Ni(II) 无活性，但发现 Chit-Co(II) 和 Chit-Mn(II) 在 Na ₂ SO ₃水溶液存在下对醋酸乙烯酯聚合具有活性. 此外，由 Chit-Co(II) 生产的聚醋酸乙烯酯 (PVAc) 与商业 PVAc 相比，其产率高于由 Chit-Mn(II) 生产的 PVAc。聚合已显示通过表面引发的原子转移自由基聚合 (SI-ATRP) 进行，所产生的 PVAc 的粘均分子量已测量为 25, 078。密度泛函理论方法已用于确定配位Chit-Co(II) 的取向并解释其对醋酸乙烯酯聚合的高效性。催化剂可重复使用性测试表明，经过七次聚合循环后，Chit-Co(II) 的活性损失很小。动力学和热力学研究表明，醋酸乙烯酯聚合是一个吸热过程，并在环境温度下进行。