Rentero Christian, Damián Jesús, Medel Asier, Fernández-Millán María, Rusconi Yolanda, Talarico Giovanni, Cuenca Tomás, Sessini Valentina, Mosquera Marta E G
Department of Organic and Inorganic Chemistry, Institute of Chemical Research "Andrés M. del Río" (IQAR), Universidad de Alcalá, Campus Universitario, 28871 Madrid, Spain.
Dipartimento di Scienze Chimiche, Università degli Studi di Napoli Federico II, Via Cintia, 80124 Napoli, Italy.
Polymers (Basel). 2022 Jul 23;14(15):2982. doi: 10.3390/polym14152982.
Two non-toxic potassium compounds, and , with a commercial oximate ligand have been prepared and fully spectroscopically characterized. Their activity as catalysts for the ring-opening polymerization (ROP) process of LLA has been studied, showing that they are extremely active and able to polymerize the monomer in a few minutes. For derivative , the presence of a crown ether in the potassium coordination sphere affects the nuclearity of the compound and consequently its solubility, with both aspects having an influence in the polymerization process. Detailed studies of the polymerization mechanism have been performed, and an unusual anionic mechanism was observed in absence of a co-initiator. Indeed, the monomer deprotonation generates a lactide enolate, which initiates the polymerization propagation. On the contrary, when a 1:1 ratio of cat:BnOH is used, a mixture of mechanisms is observed, the anionic mechanism and the activated monomer one, while from a cat:BnOH ratio of 1:2 and over, only the activated monomer mechanism is observed.
已经制备了两种无毒钾化合物以及与一种商业肟配体，并对其进行了全面的光谱表征。研究了它们作为L-丙交酯（LLA）开环聚合（ROP）过程催化剂的活性，结果表明它们具有极高的活性，能够在几分钟内使单体聚合。对于衍生物，钾配位球中冠醚的存在会影响化合物的核数，进而影响其溶解度，这两个方面都会对聚合过程产生影响。已经对聚合机理进行了详细研究，并且在没有共引发剂的情况下观察到了一种不寻常的阴离子机理。实际上，单体去质子化会生成丙交酯烯醇盐，从而引发聚合链增长。相反，当使用催化剂与苄醇（BnOH）的比例为1:1时，会观察到混合机理，即阴离子机理和活化单体机理，而当催化剂与苄醇的比例为1:2及以上时，仅观察到活化单体机理。
