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首页> 外文期刊>ACS Sustainable Chemistry & Engineering >Direct Synthesis of Alternating Polycarbonates from CO2 and Diols by Using a Catalyst System of CeO2 and 2-Furonitrile
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Direct Synthesis of Alternating Polycarbonates from CO2 and Diols by Using a Catalyst System of CeO2 and 2-Furonitrile

机译：通过使用CeO2和2-呋喃腈的催化剂体系直接合成来自CO 2和二醇的交替聚碳酸酯

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The control technique of polymer molecular weight is required for the synthesis of versatile polymers with various properties. In our previous work, we found that CeO2 + 2-cyanopyridine catalyst system was effective for the direct synthesis of alternating polycarbonates from CO2 and diols, however, the maximum average molecular weight was, similar to 1000 g mol(-1) (degree of polymerization = 7-8). In this study, we succeeded in the synthesis of alternating polycarbonates with higher molecular weight from CO2 and diols by using a catalyst system of CeO2 + 2-furonitrile. The average molecular weight reached up to 5000 g mol(-1) and could be controlled by adjusting the amount of diols and 2-furonitrile. Moreover, polycarbonate diols, polycarbonates without capping of OH groups at the ends, were obtained with the average molecular weight of similar to 2000 g mol(-1). The catalyst system was applicable to the direct polymerization of CO2 and various alpha,omega-diols, providing the corresponding alternating polymers. Comparison of CeO 2 + 2-cyanopyridine and CeO2+ 2-furonitrile catalyst systems based on the kinetics and DFT calculations showed two main causes for the formation of polycarbonates with higher molecular weight in the CeO2 + 2-furonitrile catalyst system: First, the reactivity of 2-furamide, which was formed from 2-furonitrile, with produced polycarbonate diols was lower than that of 2-picolinamide, which was formed from 2-cyanopyridine, leading to decrease of formation of ester-capped polycarbonates. Second, the adsorption of 2-furonitrile on CeO2 was weaker than that of 2-cyanopyridine, leading to low steric hindrance at the active sites of CeO2 and enabling the reaction of longer diols, such as polycarbonate diols with CO2.
机译：聚合物分子量的控制技术是合成具有各种性质的通络聚合物。在我们以前的工作中，我们发现CeO2 + 2-氰基吡啶催化剂体系对来自CO 2和二醇的交替聚碳酸酯的直接合成是有效的，然而，最大平均分子量是类似于1000g摩尔（-1）（型）聚合= 7-8）。在该研究中，通过使用CeO 2 + 2-呋喃腈的催化剂体系，我们成功地合成了来自CO 2和二醇的更高分子量的聚碳酸酯。平均分子量达到5000g mol（-1），可以通过调节二醇和2-呋喃腈的量来控制。此外，使用与2000g mol（-1）相似的平均分子量，得到聚碳酸酯二醇，没有覆盖OH基团的OH基团的覆盖物的聚碳酸酯。催化剂体系适用于CO 2的直接聚合和各种α，ω-DiOls，提供相应的交替聚合物。基于动力学和DFT计算的CeO 2 + 2-氰基吡啶和CeO2 + 2-呋喃腈催化剂体系的比较显示了CeO2 + 2-呋喃腈催化剂系统中具有较高分子量的聚碳酸酯的两种主要原因：第一，反应性由2-呋喃腈形成的2-呋喃胺低于2-氰基吡啶形成的2-吡啶胺，导致酯封端的聚碳酸酯的形成减少。其次，CeO2上的2-呋喃腈的吸附性比2-氰基吡啶的吸附较弱，导致CeO 2的活性位点处的低空间障碍，并使较长的二醇的反应，例如聚碳酸酯二醇与CO 2。

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