Creating Silicones: Exerting Control at Interfaces

尽管其成本高于有机替代品，但由于其独特的界面行为，有机硅聚合物几乎在发达经济体的每一个技术领域都有应用。由于缺乏有效的合成方法，大多数商业有机硅聚合物在分子量、支化频率和类型、官能团分布和网络结构方面都是不明确的混合物。驱动研究计划的假设是，精确结构的有机硅聚合物将提高我们增强界面的能力，从而产生具有增强性能的更高价值材料。除了纯有机硅之外，还将制备具有新亲水功能的新聚合物，以增强我们控制异质界面的能力。拟议研究的成果将是新的合成策略，从而产生新型有机硅聚合物，其应用范围从自润滑接触透镜表面到热稳定LED圆顶。使用Piers-Rubinsztajn反应（PR，R3 SiH + R 'O Silicone-> R3 SiOSilicone（或R' OAr-> R3 SiOAr）在B（C6 F5）3存在下）来产生新材料的新策略是过去5年的重要成果。结构很重要！支化有机硅表面活性剂的头基中的小的结构差异导致表面活性的大的变化。这个概念将被扩展到产生复杂的3D硅树脂结构的库，包括瓶刷聚合物，其将以混合和匹配的方式从精确的树枝状分子组装。* 界面处的调节行为需要新的途径来实现化学改性的有机硅。将开发新的无金属策略，使用黄原酸盐、腙和额外的无金属点击化学，将有机硅连接到小的聚合物链，特别是那些基于天然材料的链。亲水物将包括木质素和淀粉，例如瓜尔胶和透明质酸，因为它们与生物相容性表面相关。利用这些原理，通过用天然、可再生、可生物降解的材料稀释有机硅，将形成绿色复合材料。*实现这些结果需要彻底表征该计划中制备的聚合物和复合材料。这将包括物理测试（模量和断裂伸长率）、表面分析（粘附力（剥离测试）、XPS）以及分子表征（NMR、MS）。*实现拟议的科学目标的一个重要方面是在技术领域继续培训HQP（过去6年：32名本科生，8名硕士，13名博士生，8名PDF），如聚合物/材料合成和表征。这将提高HQP在学术界和工业界获得就业的能力，特别是位于南安大略的3家有机硅和许多聚合物公司。聚合物加工方面的培训是加拿大经济持续增长所必需的。

In spite of their higher cost than organic alternatives, silicone polymers are found in almost every technological area of developed economies because of their unique interfacial behavior. Lacking efficient syntheses, most commercial silicone polymers are ill-defined mixtures with respect to molecular weight, frequency and type of branching, distribution of functional groups and network structures. The hypothesis driving the research program is that silicone polymers of precise structure will improve our ability to reinforce interfaces, leading to higher value materials with enhanced properties. In addition to pure silicones, new polymers with new hydrophilic functionalities will be prepared that can enhance our ability to control heterogeneous interfaces. The outcomes of the proposed research will be new synthetic strategies leading to novel silicone polymers with applications ranging from self-lubricating contact lens surfaces to thermally stable LED domes.***New strategies to use the Piers-Rubinsztajn reaction (PR, R3SiH + R'OSilicone -> R3SiOSilicone (or R'OAr -> R3SiOAr) in the presence of B(C6F5)3) to create novel materials was an important outcome of the last 5 years. Structure matters! Small structural differences in the head group of branched silicone surfactants led to large changes in surface activity. This concept will be extended to yield a library of complex 3D silicone structures, including bottlebrush polymers, that will be assembled from precise dendrons in a mix and match' manner. ***Tuning behavior at interfaces requires new routes to hydrophilically modified silicones. New metal free strategies to link silicone to small and polymeric hydrophiles, particularly those based on natural materials, using xanthates, hydrazones and additionalmetal free click chemistry will be developed with hydrophiles. Hydrophiles will include lignin and saccharides such as guar and hyaluronic acid because they are associated with biocompatible surfaces. Green composites will be formed using these principles, by diluting of silicones with natural, renewable, biodegradable materials.***Achieving these outcomes requires thorough characterization of the polymers and composites prepared in this program. This will include physical testing (modulus and extension at break), surface analysis (adhesion (peel tests), XPS), in addition to molecular characterization (NMR, MS).***An important aspect of reaching the proposed scientific objectives is continued training of HQP (last 6 years: 32 undergrad, 8 MSc, 13 PhD students, 8 PDFs) in technical areas, such as polymer/materials synthesis and characterization. This will enhance the HQP's ability to attain employment in academia and industry, particularly the 3 silicone and the many polymer companies located in Southern Ontario. Training in polymer processing is required for Canada's continued economic growth.**