Dynamics of Functional Polymers with Reversible Bonds: The Role of Associating Group Aggregates

非技术概述：由聚合物分子之间的可逆化学键形成的缔合聚合物具有其他材料无法实现的独特宏观特性和功能，包括自修复和时间可编程功能。此外，它们形成了对可持续发展至关重要的可回收塑料材料。然而，如何控制这些新型聚合物材料的宏观性能的详细定量理解仍然是一个挑战。提出的研究通过将广泛的实验技术与开发和测试连接分子尺度过程和宏观特性的新理论模型方法相结合来解决这一挑战。在这项研究中开发的知识将是合理设计新颖的可回收聚合物的核心，具有独特的，自我修复和刺激响应特性。它将对包括材料科学、物理学、化学和生物物理学在内的各个科学和工程领域产生重大影响。该项目的一个重要重点是通过研究生和本科生积极参与研究与教育相结合。该项目还促进与国家用户设施和国际合作的积极合作。技术概述：通过可逆的分子间相互作用形成的缔合聚合物，包括广泛的基本和技术上重要的材料，比传统聚合物具有更好的可回收性。合理的设计、合成和制造新型缔合聚合物需要对缔合基团的局部可逆相互作用和相分离如何影响这些材料的宏观性质有深刻的基本理解。尽管过去有广泛的关注和努力，但对缔合聚合物熔体动力学的详细定量理解仍然有限。这阻碍了具有理想性能的新型功能材料的开发。计划研究的主要目标是加深对不同时间和长度尺度上缔合聚合物动力学的基本理解，特别关注缔合基团聚集体的作用。在本研究中，将结合流变学、介电光谱、差示扫描量热法、光散射和中子散射光谱，研究相关聚合物的链和段动力学以及粘弹性特性。它将辅以使用小角度x射线和中子散射的结构分析，并将为现有理论提供广泛的实验测试。本研究将加深对微观参数控制缔合聚合物宏观性质的基本认识，特别是内在非均质性的作用。这将有助于合理设计具有独特粘弹性和自愈特性的材料，以及具有可调时间编程和刺激响应特性的新型功能材料的设计。从更广泛的角度来看，它也可能对许多生物材料的理解产生强烈的影响，其中可逆键和相互作用起着至关重要的作用。该奖项反映了美国国家科学基金会的法定使命，并通过基金会的智力价值和更广泛的影响审查标准进行了评估，认为值得支持。

NON-TECHNICAL SUMMARY:Associating polymers formed by reversible chemical bonds between polymer molecules have unique macroscopic properties and functionalities not achievable in other materials, including self-healing and time-programmable functions. Moreover, they form recyclable plastic materials critical for sustainability. However, detailed quantitative understanding of how to control macroscopic properties of these novel polymeric materials remains a challenge. The proposed research addresses this challenge by combining a broad range of experimental techniques with development and testing of new theoretical model approaches connecting molecular-scale processes to macroscopic properties. The knowledge developed in this research will be central to the rational design of novel recyclable polymers with unique, self-healing, and stimuli-responsive properties. It will have strong impact on various fields of science and engineering, including materials science, physics, chemistry and biophysics. A significant focus of the project is integration with education through active involvement of graduate and undergraduate students in research. The project also promotes active collaborations with national user facilities and international collaborations. TECHNICAL SUMMARY:Associating polymers, formed by reversible intermolecular interactions, include a wide spectrum of fundamentally and technologically important materials with better recyclability than traditional polymers. Rational design, synthesis, and fabrication of novel associating polymers require a deep fundamental understanding of how the local reversible interactions and phase separation of the associating groups affect the macroscopic properties of these materials. Despite extensive attention and efforts in the past, detailed quantitative understanding of dynamics in the melts of associating polymers remains limited. This hinders development of novel functional materials with desired properties. The main goal of the planned research is to deepen the fundamental understanding of dynamics in associating polymers on different time and length scales with special focus on the role of associating group aggregates. In this research, the chain and segmental dynamics and the viscoelastic properties of associating polymers will be studied by a combination of rheology, dielectric spectroscopy, differential scanning calorimetry, and light- and neutron scattering spectroscopies. It will be complemented by analysis of structure using small angle X-ray and neutron scattering, and will provide broad-based experimental tests of existing theories. The proposed research will deepen fundamental understanding of microscopic parameters controlling macroscopic properties of associating polymers, especially the role of intrinsic heterogeneities. This will be instrumental for a rational design of materials with unique viscoelastic and self-healing properties, as well as for design of novel functional materials with tunable time programmed and stimuli-responsive properties. From a broader perspective, it might also have strong impact on understanding of many biological materials where reversible bonding and interactions play a critical role..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.