Synthesis of Organometallic Catalysts for Switchable Polymerisations Using Renewable Resources: Next Generation Sustainable Elastomers and Engineerin

塑料是我们日常生活中遇到的一些最重要的材料。从包装到我们的衣服和我们心爱的电子设备，塑料材料已经成为现代社会的基石。这些塑料是由一种叫做聚合物的分子组成的。聚合物是由许多被称为单体的较小的积木分子组成的长链分子。使用的单体类型和它们连接在一起的顺序决定了塑料是硬的还是软的，是脆的还是韧的。因此，化学家可以通过决定链中包括哪些单体以及它们的排列方式来控制聚合物的性质。这使得我们可以为不同的应用创造不同的塑料。我们使用的大多数塑料都是由来自化石燃料的单体组成，因此是不可持续的。石化衍生聚合物还能够在环境中停留令人难以置信的长时间而不降解，因此它们造成的污染可能会对许多生物产生致命的后果。这导致化学家探索从植物提取物甚至二氧化碳等生物来源制造可生物降解聚合物的可能性，二氧化碳是导致全球变暖的主要原因。不幸的是，与化石燃料衍生的同类相比，仅由这些可持续单体中的一种制成的聚合物的机械和热性能较差。然而，已有研究表明，将两种或两种以上的生物衍生单体结合在一起可以生产出具有令人印象深刻的性能的塑料。一种选择是通过形成嵌段共聚物来实现这些性能的改善。这是一种含有化学上可区分的单体链段的聚合物，这些链段连接在一起形成一条链。2014年，一种制造可持续嵌段共聚物的新方法被发现，称为开关催化。这一新发现使嵌段共聚物的生产变得容易，并具有精确的单体序列。自那以后，开关催化已被用于生产一系列不同的可持续聚合物，其性能比任何一个组成链段都要好。然而，如果这些新的可持续塑料要真正与它们的石化同行竞争，仍然需要新的化学策略来制造更广泛的材料和提高制造过程的效率。这个项目将研究性能的改善和用于制造它们的催化剂。在第一阶段，将探索一系列允许对使用开关催化制造的现有可持续塑料进行改性的化学方法。通过引入少量廉价和富含稀土的金属离子，有可能使聚合物链形成网络，并提供进一步的结构刚性。这些新材料被称为离聚体，目前人们还不太清楚可生物降解离聚体的潜力，但这一问题将通过目前的研究来解决。该项目属于EPSRC‘制造未来’研究领域，将涉及与工程部合作测试生产的新型塑料。所有材料的强度、韧性、硬度和弹性将在聚合物、离聚体和网络的系统系列中进行比较。由于聚合物-金属键的可逆性，这些离聚体还应该显示出在破裂或断裂的情况下自我修复或愈合的能力。此外，与橡胶等传统的交联聚合物不同，对这些材料进行再加工和回收应该是可行的。本项目还将研究塑料的自愈行为和回收潜力。总体目标是推导出有效的生产路线，以获得具有良好机械性能的生物衍生、可回收和可生物降解的产品，这可能有助于提高塑料的可持续性

Plastics are some of the most important materials we encounter in our everyday lives. From packaging to our clothes and our beloved electronic devices, plastic materials have become a cornerstone of modern society. These plastics are made up of a type of molecule called polymers. Polymers are long-chain molecules made up of lots of smaller building block molecules known as monomers. Both the type of monomers used and the order they are connected together in determine whether a plastic is hard or soft, brittle or tough. Therefore, chemists can control the properties of a polymer by deciding which monomers to include in the chain and how they are arranged. This allows for the creation of different plastics for various applications.The majority of plastics we use are made up of monomers that are sourced from fossil fuels and are therefore unsustainable. Petrochemical derived polymers are also able to remain in the environment for incredibly long periods of time without degrading and the pollution they cause as a result can have potentially fatal consequences to many living organisms. This has led chemists to explore the possibility of making biodegradable polymers from bio-derived resources such as plant extracts or even carbon dioxide, the gas primarily responsible for global warming. Unfortunately, polymers made of only one of these sustainable monomers have poorer mechanical and thermal properties compared to their fossil-fuel derived cousins. However, it has been shown that combining two or more bio-derived monomers together can result in the production of plastics with impressive properties. One option is to achieve these property improvements through the formation of block copolymers. These are a type of polymer containing chemically distinguishable segments of monomers that are joined together in one chain. In 2014, a new method of making sustainable block copolymers was discovered called switch catalysis. This new discovery allows for block copolymers to be produced easily and with a precise sequence of monomers.Switch catalysis has since been used to produce a range of different sustainable polymers with better properties than either of the constituent blocks. However, if these new sustainable plastics are to truly compete with their petrochemical counterparts, new chemical strategies are still needed to make a broader range of materials and to improve the efficiency of the manufacturing process.This project will investigate both the property improvements and the catalysis used to make them. In the first phase, a series of chemistries allowing for the modification of existing sustainable plastics made using switch catalysis will be explored. By introducing a small volume fraction of inexpensive and earth-abundant metal ions, it may be possible to network the polymer chains and provide further structural rigidity. These new materials are called ionomers and currently the potential for biodegradable ionomers is not well understood but this will be addressed through the current investigation.This project falls within the EPSRC 'manufacturing the future' research area and will involve collaboration with the department of engineering to test the new types of plastic produced. The strength, toughness, stiffness and elasticity of all the materials will be compared within systematic series of polymers, ionomers and networks. These ionomers should also display the ability to self-repair or heal in the event of cracking or snapping due to the reversible nature of the polymer-metal bonds. Furthermore, unlike traditionally cross-linked polymers, such as rubber, it should be feasible to reprocess and recycle these materials. The self-healing behaviour and recycling potential will also be investigated in this project.The overall goal is to deduce efficient manufacturing routes to bio-derived, recyclable and biodegradable products showing excellent mechanical properties and which may help improve sustainability of plastics