Synthesis of polymeric materials derived from abundant natural feedstocks using non-toxic heavy metals

合成聚合物是现代世界中普遍存在的材料。绝大多数是从石化原料中提取的，在自然环境中无法降解。据估计，到2015年底，所有产生的塑料垃圾中有78%被丢弃在垃圾填埋场或自然环境中，而只有9%被回收利用。商品聚合物的持续存在导致了严重的陆地和海洋污染。解决这一问题的一个可行战略是用从丰富的天然原料中提取的可持续聚合物取代石油聚合物。催化是将自然资源转化为能够在性能和成本方面与现有合成聚合物竞争的聚合物材料的关键。合适的催化剂系统可以提高合成过程的效率，并可以针对目标应用调整聚合物的性能。该项目属于EPSRC制造未来的主题。该项目旨在开发具有无毒重金属(如铋、铟和稀土元素)的新型催化剂，用于合成可持续聚合物。该项目最初的重点是铋，这是最环保的重金属之一。开发的系统将作为催化剂在一系列合成方法中进行测试，以使用天然原料生产可持续聚合物。其中之一是来自富含淀粉的生物质的丙交酯单体的开环聚合。这就产生了聚乳酸，这是一种生物可降解和生物兼容的聚合物，已经在医药、包装和纤维技术中得到了应用。目前，聚乳酸的工业生产是在恶劣的条件下使用含有有毒金属锡的催化剂。使用更环保的催化剂系统作为防止最终聚合物产品中有毒残留物的一种手段引起了极大的兴趣。虽然与轻元素相比，含有重金属的催化剂的研究还很少，但它们显示出独特的反应途径和提高活性的潜力。开发的催化剂系统还将用于将主要环境污染物二氧化碳转化为聚碳酸酯聚合物。虽然聚碳酸酯的传统合成依赖于危险的石化原料，但二氧化碳可以用来取代高达50%的聚合物质量，从而提供了一个机会，既减少了碳足迹，又将工业废物转化为高价值的化学品。新的重金属催化剂体系的优化可以拓宽用于生产可持续聚合物的可行催化策略的范围，并为合理的聚合催化剂设计提供新的见解。

Synthetic polymers are ubiquitous materials in the modern world. The vast majority are derived from petrochemical feedstocks and are unable to degrade in natural environments. It is estimated that by the end of 2015, 78% of all ever produced plastic waste was discarded in landfills or natural environment, whereas only 9% was recycled. The persistence of commodity polymers has resulted in severe land and marine pollution. A viable strategy to address this issue involves replacing petroleum based polymers with sustainable polymers derived from abundant natural feedstocks. Catalysis is key to enabling the transformation of natural resources into polymeric materials capable of competing with existing synthetic polymers in terms of both performance and cost. Suitable catalyst systems can improve the efficiency of synthetic processes and can tune polymer properties for target applications. This project falls within the EPSRC Manufacturing the Future theme. The project aims to develop novel catalysts featuring non toxic heavy metals (such as bismuth, indium and lanthanides) for the synthesis of sustainable polymers. The initial focus of this project is on bismuth, as one of the most environmentally-benign heavy metals. The developed systems will be tested as catalysts in a series of synthetic methods to produce sustainable polymers using natural feedstocks. One of these is the ring opening polymerisation of lactide monomers derived from starch-rich biomass. This produces poly(lactic acid), a biodegradable and biocompatible polymer that has already found applications in medicine, packaging and fibre technology. Currently, poly(lactic acid) is industrially produced in harsh conditions using a catalyst containing a toxic tin metal. The use of more environmentally benign catalyst systems is of great interest as a means of preventing toxic residues in final polymer products. Although catalysts containing heavy metals have been studied scarcely compared to lighter elements, they have shown potential for unique reaction pathways and enhanced activity. The developed catalyst systems will also be investigated for the conversion of carbon dioxide, a major environmental pollutant, into polycarbonate polymers. While a traditional synthesis of polycarbonates relies on hazardous petrochemical raw materials, carbon dioxide could be used to replace up to 50% of a polymer's mass, thereby offering an opportunity to both reduce the carbon footprint and turn an industrial waste into high value chemicals. The optimisation of new heavy metal based catalyst systems could broaden the scope of viable catalytic strategies used to produce sustainable polymers and afford new insights into rational polymerisation catalyst design.