Tunable Enthalpic and Entropic Interactions in Blends of Block Copolymers and Polymeric Additives

非技术性SUMMARY嵌段共聚热塑性弹性体(TPE)是许多行业众多产品的关键部件，包括医疗器械、电信和建筑。这些材料也显示出作为水净化和燃料电池膜的前景。然而，热塑性弹性体面临长期稳定性问题的挑战，这限制了它们在现有应用中的使用寿命，并阻碍了它们在清洁水和清洁空气技术中的采用。这项研究计划将通过使用一类相互作用调节的聚合物添加剂来定制嵌段共聚TPE的结构，从而为应对这一挑战奠定关键基础，从而能够仔细研究控制观察到的机械性能的分子和介观属性。这些知识将指导高性能嵌段共聚热塑性弹性体的开发，使其在长时间内保持其机械完整性。此外，这些原理可以扩展到作为本研究计划重点的模型化学之外，从而促进基于可再生原料的新型热塑性弹性体的开发。Stein和Kilbey之间的合作将为研究生和本科生提供聚合物合成和先进材料表征技术方面的培训。与实验室研究相辅相成的是1)在UTK为研究生举办的以聚合物物理基础为重点的年度研讨会；以及2)新开设的研究生选修课，提供数据分析计算工具方面的培训，介绍处理、分析和组织大量实验数据的方法。UTK由NSF支持的ASPIRE和TLSAMP项目促进了本科生的参与，这些项目为来自代表性不足群体的学生，特别是来自阿巴拉契亚地区的第一代大学生提供资助的研究机会。技术总结本研究项目将考察线性三嵌段共聚物和相互作用调节的随机共聚物(PRC)添加剂的共混体系的结构和性能。通过改变PRC添加剂的组成、相对分子质量和结构，将定制控制这些组分的相容的焓和熵驱动力，从而实现对大参数空间的系统询问。三个相关的研究推力将检验这一关键假设，即PRC添加剂可以通过调节纳米PS区域内的局部结构来提高宏观力学性能。建议中定义的局部结构包括链构象、每条链的界面面积和PRC添加剂的空间分布等属性。这项研究的结果将提供一个框架，指导可混溶聚合物添加剂的设计，以提高特定的热塑性弹性体性能，包括拉伸强度、延展性或抗蠕变性能。这将使嵌段共聚物膜的设计能够在很长时间内保持其机械性能，这对下一代能源转换设备和水净化技术至关重要。虽然这项研究计划将用模型苯乙烯材料来实施，但通过中国添加剂的设计阐明的基本原理预计将直接与面临类似挑战、具有长期稳定性的其他类别的材料相关，包括那些来自可再生资源的材料。学生将接受聚合物化学、聚合物物理、大数据集的高通量分析和先进材料表征方面的培训。这些技术技能对于一个依赖材料科学和工程的社会的竞争力和终身贡献至关重要。此外，为代表性不足群体的学生提供机会和直接指导，将有助于激励和激励年轻学习者，催化他们的成功，并点燃好奇心，最终促进多样化和具有竞争力的劳动力的发展。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 SUMMARYBlock copolymer thermoplastic elastomers (TPEs) are critical components in numerous products across many industries, including medical devices, telecommunications and construction. These materials also show promise as membranes for water purification and fuel cells. However, TPEs are challenged by issues with long-term stability, which limits their service life in established applications and prevents their adoption in clean water and clean air technologies. This research program will lay critical groundwork to address this challenge by tailoring the structure of block copolymer TPEs with a class of interaction-tuned polymer additives, thereby enabling careful studies of the molecular and mesoscale attributes that control the observed mechanical properties. This knowledge will guide the development of high-performance block copolymer TPEs that maintain their mechanical integrity over long timescales. Furthermore, the principles can be extended beyond the model chemistries that are the focus of this research program, thereby facilitating the development of new TPEs based on renewable feedstocks. The collaboration between Stein and Kilbey will provide graduate and undergraduate students with training in polymer synthesis and advanced materials characterization techniques. Laboratory research is complemented by 1) an annual workshop for graduate students at UTK focused on Fundamentals of Polymer Physics; and 2) a new graduate elective that provides training in Computational Tools for Data Analysis, which introduces methods to process, analyze and organize large amounts of experimental data. Undergraduate student involvement is facilitated by the NSF-supported ASPIRE and TLSAMP programs at UTK, which provide funded research opportunities for students from under-represented groups, especially first-generation college students from the Appalachia region. TECHNICAL SUMMARYThis research program will examine structure and properties in blends of linear triblock copolymers and interaction-tuned random copolymer (PrC) additives. The enthalpic and entropic driving forces that control miscibility of these constituents will be tailored by changing the composition, molecular weight and architecture of the PrC additives, enabling a systematic interrogation of a large parameter space. Three related research thrusts will test the key hypothesis that PrC additives can enhance macroscopic mechanical properties by modulating the local structure within nanoscopic PS domains. The local structure, as defined in the proposal, includes attributes such as chain conformations, interfacial area per chain, and the spatial distribution of PrC additives. Outcomes of this research will provide a framework that guides the design of miscible polymer additives to enhance specific TPE properties, including tensile strength, ductility, or creep resistance. This will allow for the design of block copolymer membranes that preserve their mechanical properties over long time scales, which is critical for next-generation energy conversion devices and water purification technologies. Although this research program will be implemented with model styrenic materials, the fundamental principles elucidated through the design of PrC additives are envisioned to be directly relatable to other classes of materials that face similar challenges with long-term stability, including those derived from renewable resources. Students will be trained in polymer chemistry, polymer physics, high-throughput analysis of large data sets, and advanced materials characterization. These technical skills are critical for competitiveness in and lifelong contributions to a society dependent on materials science and engineering. Additionally, opportunities provided to and direct mentoring of students from under-represented groups will help to inspire and stimulate young learners, catalyze their success, and ignite curiosity, ultimately fostering the development of a diverse and competitive workforce. .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.