Creating Silicones: Exerting Control at Interfaces

尽管有机硅聚合物的成本高于有机替代品，但由于其独特的界面行为，在发达经济体的几乎所有技术领域都可以找到它们的身影。由于缺乏有效的合成，大多数商用有机硅聚合物在相对分子质量、支化频率和类型、官能团分布和网络结构方面都是定义不明确的混合物。推动这项研究计划的假设是，精确结构的有机硅聚合物将提高我们加强界面的能力，从而产生具有增强性能的更高价值的材料。除了纯有机硅外，还将制备具有新的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导致新型有机硅聚合物的新合成策略，应用范围从自润滑隐形眼镜表面到热稳定的LED穹顶。*在B(C6F5)3存在下使用Piers-Rubinsztajn反应(PR，R3SiH R‘OSilicone-&gt；R3SiOSilicone(或R’OAr-&GT；R3SiOAr；R3SiOAr；R3SiOAr)创造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头部基团的微小结构差异导致表面活性发生较大变化。这一概念将被扩展，以产生一个复杂的3D硅胶结构库，包括瓶刷聚合物，将以混合匹配的方式由精确的树枝组装而成。*调整界面行为需要新的亲水性改性有机硅路线。新的无金属策略，将有机硅与小的和聚合物的亲水性，特别是那些基于天然材料，使用黄原酸酯，肼和附加的无金属点击化学将开发与亲水性。亲水性将包括木质素和糖类，如瓜尔胶和透明质酸，因为它们与生物相容性表面相关。绿色复合材料将利用这些原则，通过用天然的、可再生的、可生物降解的材料稀释有机硅来形成。*要实现这些结果，需要对本计划中制备的聚合物和复合材料进行彻底的表征。这将包括物理测试(模数和断裂伸长率)，表面分析(附着力(剥离测试)，XPS)，以及分子表征(核磁共振，MS)。*实现拟议的科学目标的一个重要方面是继续培训HQP(最近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。这将增强HQP在学术界和工业界的就业能力，特别是位于安大略省南部的3有机硅和许多聚合物公司。加拿大的持续经济增长需要聚合物加工方面的培训。**

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.**