NSF-BSF: Emergent Rheology of Blends Containing Supramolecular Polymers

非技术摘要：Shenhar教授（耶路撒冷希伯来大学）和克雷格教授（美国杜克大学）之间的这一合作项目将测试一种特殊的聚合物家族，称为超分子聚合物，代表了下一代流动性能改性剂的一种有前途的和未开发的材料类别的假设。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;可以有效制造的聚合物范围;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，添加剂用于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。众多挑战促使开发新的、可推广的和可扩展的流变改性剂策略，这些策略在较低负载下提供增强的性能，并且可以针对广泛的应用进行定制。驱动因素包括：人们对流变改性剂浸出的潜在健康和环境影响的认识不断提高;全球对能源效率的关注日益增加;新制造技术的出现-特别是增材制造-具有定制流变要求;认识到需要改进回收途径。其中分子单元通过可逆键保持在一起的超分子聚合物将用于生产塑料的分子添加剂在高温下的软化作用与赋予塑料材料在环境温度下有用的机械性能的典型聚合物样行为结合在一起。该项目将把Shenhar开发的超分子聚合物的结构控制与克雷格开发的流变学专业知识相结合，以追求解锁这类新流变改性剂的基本原理。 技术概要：该项目解决了有关流变学改性的关键性基本问题，这些流变学改性可能通过将超分子聚合物混入传统聚合物熔体中来实现。将使用合成和表征的组合来测试和改进这组相对未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改性剂的一个有前途的和未开发的材料类别。超分子聚合物联合收割机结合了低分子量添加剂的增塑作用和可通过分子结构调节的牛顿和非牛顿流变学的丰富组合。尽管超分子聚合物有希望，但它们在很大程度上未被用作流变改性剂。该研究计划旨在为这两种材料的新混合物的流变学提供新的和可推广的原则。拟议的工作力求：（ii）表征超分子和共价组分的共混物的流变性，建立超分子聚合物赋予共价熔体独特流变行为的设计原理;（iii）探索超分子共混作为传统难加工聚合物的熔融挤出和增材制造（3D打印）的促进剂。该奖项反映了NSF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.