Creating and Using More Sustainable Silicones

有机硅聚合物(通常基于(Me2OSi)n单体)通常是低技术含量浴缸密封胶以及伤口敷料、LED灯等高科技应用中的关键成分，因为它们具有不同寻常且极具价值的特性。它们的使用量/使用量通常比其他材料低得多，而且它们在环境中表现出对二氧化碳、水和沙子的有效分解。然而，有机硅的成本高于有机聚合物，因为它们的合成所需的能量输入非常高(通过金属硅)。与其他聚合物和塑料一样，必须通过以下方式使有机硅更可持续：使用更绿色的工艺合成其原料；开发新的绿色反应，包括固化化学(例如，避免使用有毒金属催化剂)以产生有用的产品；以及减少产生的废物。这项研究计划将通过以下方式提高有机硅聚合物的可持续性：i)使用有机硅作为增强聚合物回收的试剂，ii)制备所需性能范围较窄的精密有机硅，以便特定应用所需的有机硅更少，iii)使用可再生的、环境可接受的材料稀释有机硅，以获得具有有趣性能的复合材料。使用Piers-Rubinsztajn反应将制备精密的有机硅；SH、NH等官能团将在线型、支化和网状聚合物上精确排列。简单、高产率的反应将在选定的地点引入天然产品。这些成分包括金属离子结合(螯合)部分、糖和蛋白质，它们将向有机硅传递抗菌活性和/或在水中膨胀的能力，用于伤口敷料或能量衰减。硅橡胶还将使用天然生物聚合物进行增强，包括纤维素、口香糖、淀粉和废羊毛等蛋白质。将产生高质量的橡胶，但当堆肥时，材料将经历天然材料和硅胶的快速分解。以可控的方式将天然材料引入有机硅将需要新的聚合物改性合成策略。这项工作的一个重要成果是开发了将憎水有机硅与亲水天然材料联系起来的有效方法。这些将导致具有新性质的新硅酮库，可以在不断发展的应用中加以利用。天然产品将增强每公斤有机硅聚合物的可持续性，根据总能量投入、所使用的原料、可重复使用/可回收/可堆肥来判断。同样重要的是，我们将制定可预测的规则，将有机硅结构与性能联系起来，涉及变量：有机硅类型、天然产品、连接剂；以及它们的物理和化学结合方式。这些规则和准备的化合物，有可能被加拿大有机硅行业应用。更大的影响将是在研究期间培训的HQP。

Silicone polymers (typically based on (Me2OSi)n) monomers) are frequently key constituents in low tech - bathtub sealant - to high tech applications - wound dressings, LED lights, etc., because of their unusual and highly valuable properties. They are often used at much lower quantities/application than other materials and they exhibit efficient breakdown in the environment to CO2, H2O and sand. However, silicones cost more than organic polymers because of the very high energy input required for their synthesis (via silicon metal). Like other polymers and plastics there is an imperative to make silicones more sustainable by: using greener processes for the synthesis of their starting materials; the development of new green reactions, including cure chemistries (e.g., avoiding toxic metal catalysts) to create useful products; and producing less waste. This research program will improve the sustainability of silicone polymers by: i) using silicones as reagents for enhanced recovery of polymers, ii) preparing precise silicones with narrow ranges of desired properties so that less silicone is needed for given applications, iii) dilute the silicones with renewable, environmentally acceptable materials to give composites with interesting properties. Precise silicones will be prepared using the Piers-Rubinsztajn reaction; functional groups like SH, NH will be arrayed in precise locations on linear, branched and network polymers. Simple, high yielding reactions will introduce natural products at selected locations. These constituents include metal ion binding (chelating) moieties, sugars, and proteins that will convey to the silicones antibacterial activity and/or the ability to swell in water for wound dressings, or for energy damping. Silicone rubbers will also be reinforced with natural biopolymers including cellulose, gums, starch, and proteins like waste wool. High quality rubbers will result but, when composted, the materials will undergo fast breakdown of both the natural material and silicone. Bringing natural materials into silicones in a controlled way will require new synthetic strategies for polymer modification. An important outcome of this work is the development of effective methods to link water repellent silicones to water loving natural materials. These will lead to libraries of new silicones with new properties that can be exploited in evolving applications. The natural product will imbue enhanced sustainability of silicone polymers per kg, as judged by total energy input, feedstocks used, reusability/recyclability/compostability. As importantly, we will develop predictable rules relating silicone structure to properties, with respect to the variables: type of silicone, natural product, linker; and the physical and chemical ways that they have been combined. These rules and the compounds prepared, have potential for application by Canadian silicone industries. The larger impact will be the HQP trained during the research period.