NSF-BSF: Emergent Rheology of Blends Containing Supramolecular Polymers

非技术总结：Shenhar教授（希伯来大学，耶路撒冷）和Craig教授（杜克大学，美国）之间的这个合作项目将测试一个假设，即一种特殊的聚合物家族，被称为超分子聚合物，代表了下一代流动性能调节剂的有前途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；产品的特性和性能，包括化妆品、药品和涂料；塑料制品的回收利用。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“流变改性剂”的产品的全球市场目前超过70亿美元/年。许多挑战促使开发新的、通用的、可扩展的流变改性剂策略，这些策略可以在更低的负载下提供更高的性能，并且可以针对广泛的应用进行定制。驱动因素包括：人们越来越意识到流变改性剂浸出对健康和环境的潜在影响；全球更加关注能源效率；具有定制流变要求的新制造技术（尤其是增材制造）的出现；认识到需要改善回收途径。超分子聚合物，其中的分子单元通过可逆键结合在一起，结合了用于生产塑料的高温下分子添加剂的软化作用和典型的聚合物样行为，赋予塑料材料在环境温度下有用的机械性能。该项目将结合Shenhar开发的超分子聚合物的结构控制与Craig开发的流变学专业知识，追求将解锁这类新型流变改性剂的基本原理。技术概述：该项目解决了一些关键的、基本的问题，这些问题是通过将超分子聚合物混合到传统聚合物熔体中可能产生的流变性变化。合成和表征的结合将用于测试和完善这种相对未开发的材料的定量结构-活性关系。超分子聚合物代表了下一代流变改性剂的一个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量添加剂的塑化效果和丰富的牛顿和非牛顿流变学组合，可以通过分子结构进行调节。尽管它们很有前途，但超分子聚合物在很大程度上没有被用作流变改性剂。该研究计划旨在为这两种材料类别的新共混物的流变学提供新的和可推广的原则。提出的工作寻求：(i)对每个超分子组分的独特流变性有一个强有力的理解，包括迄今为止未探索的各自熔融相的流变性；（ii）表征超分子和共价组分共混物的流变性，建立设计原则，通过这些原则，超分子聚合物赋予共价熔体独特的流变性能；（iii）探索超分子共混作为传统难处理聚合物的熔体挤出和增材制造（3D打印）的促进剂。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.