NSF-BSF: Emergent Rheology of Blends Containing Supramolecular Polymers

非技术摘要：希伯来大学耶路撒冷希伯来大学的沈哈尔教授和美国杜克大学的克雷格教授之间的这个合作项目将检验这样一个假设，即一种特殊的聚合物家族，称为超分子聚合物，代表着下一代流动特性改进剂的一种有前途的和尚未开发的材料类别。聚合物熔体的流动决定了广泛的社会影响，包括：与聚合物加工相关的巨大能源消耗；可有效制造的聚合物的范围；产品的性质和性能，包括化妆品、药品和涂料；以及塑料产品的回收。因此，添加剂被用来影响聚合物熔体的流动性能。这些被称为“流变学改进剂”的产品的全球市场目前每年超过70亿美元。众多挑战推动了新的、可推广和可扩展的流变学改进剂策略的开发，这些策略可以在较低的负载下提高性能，并可以为广泛的应用量身定做。驱动因素包括：对流变学改性剂浸出的潜在健康和环境影响的认识日益增强；全球对能源效率的关注增加；具有定制流变性要求的新制造技术--特别是添加剂制造的出现；对改进回收途径的必要性的认识。超分子聚合物中的分子单元通过可逆键连接在一起，它将用于生产塑料的分子添加剂在高温下的软化作用与典型的类似聚合物的行为结合在一起，赋予塑料材料在常温下有用的机械性能。该项目将结合沈哈尔开发的超分子聚合物的结构控制和Craig开发的流变学专业知识，以追求解锁这一新型流变学改进剂的基本原理。技术概述：该项目解决了有关通过将超分子聚合物混合到传统聚合物熔体中而可能进行的流变学改性的关键的基本问题。合成和表征的结合将被用来测试和提炼这组相对未被探索的材料的定量结构-活性关系。超分子聚合物代表了下一代流变学改进剂的一种很有前途和尚未开发的材料类别。超分子聚合物结合了低分子添加剂的塑化效果和丰富的牛顿和非牛顿流变性组合，可以通过分子结构进行调节。尽管超分子聚合物前景看好，但它们在很大程度上没有被用作流变学改进剂。该研究计划试图为这些两种材料类别的新混合物的流变学提供新的和普遍的原理。拟议的工作旨在：(I)深入了解每一超分子组分的独特流变学，包括其各自熔体相的迄今未探索的流变学；(Ii)表征超分子和共价组分共混物的流变学，建立超分子聚合物赋予共价熔体独特流变行为的设计原则；(Iii)探索超分子共混作为传统难熔聚合物熔体挤出和添加剂制造(3D打印)的促进剂。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

NON_TECHNICAL SUMMARY:This collaborative project between Professors Shenhar (Hebrew University, Jerusalem) and Craig (Duke University, USA) will test the hypothesis that a special family of polymers, termed supramolecular polymers, represent a promising and untapped material class for next-generation flow-property modifiers. The flow of polymer melts dictates a wide range of societal impacts, including: the enormous energy consumption associated with polymer processing; the range of polymers that can be efficiently manufactured; the properties and performance of products, including cosmetics, pharmaceuticals, and coatings; and, the recycling of plastics products. As a result, additives are used to influence the flow properties of polymer melts. The global market for these products, termed “rheology modifiers,” currently exceeds $7 billion/yr. Numerous challenges motivate the development of new, generalizable and scalable strategies for rheology modifiers that give enhanced performance at lower loading and can be tailored for a broad range of applications. Drivers include: growing awareness of the potential health and environmental impacts of rheology modifier leaching; increased global focus on energy efficiency; emergence of new manufacturing technologies – especially additive manufacturing – with bespoke rheological requirements; recognition of the need for improved recycling pathways. Supramolecular polymers, in which the molecular units are held together by reversible bonds, combine the softening effects of molecular additives at the high temperatures used for the production of plastics with the typical polymer-like behavior that imparts plastic materials their useful mechanical properties at ambient temperature. This project will combine the structural control of supramolecular polymers developed by Shenhar with the rheological expertise developed by Craig to pursue fundamental principles that will unlock this new class of rheology modifiers. TECHNICAL SUMMARY:This project tackles critical, fundamental questions about the rheological modifications that are possible through the blending of supramolecular polymers into traditional polymer melts. A combination of synthesis and characterization will be used to test and refine quantitative structure-activity relationships for this relatively unexplored set of materials. Supramolecular polymers represent a promising and untapped material class for next-generation rheology modifiers. Supramolecular polymers combine the plasticizing effects of low-molecular weight additives with a rich combination of Newtonian and non-Newtonian rheology that can be tuned through molecular structure. Despite their promise, supramolecular polymers are largely unutilized as rheology modifiers. The research plan seeks to provide new and generalizable principles for the rheology of these new blends of two material classes. The proposed work seeks: (i) to develop a robust understanding of the unique rheology of each supramolecular component, including the heretofore unexplored rheology of their respective melt phases; (ii) to characterize the rheology of blends of supramolecular and covalent components, establishing design principles through which the supramolecular polymer confers unique rheological behavior to the covalent melt; (iii) to explore supramolecular blending as a facilitator of melt extrusion and additive manufacturing (3D printing) of traditionally intractable polymers. .This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.