Understanding the role of conserved dynamic covalent junctions on block copolymer and network self-assembly

嵌段共聚物用于许多应用中，例如环氧树脂、电池电解质和弹性服装，并且因其将两种功能联合收割机结合到一种材料中的能力而受到重视。这种能力来自于将两个或多个由不同化学单元（称为单体）组成的聚合物链结合在一起。不同的化学单体导致聚合物的不同嵌段分离，如油和水。然而，由于它们键合在一起，结果是小域，由一个嵌段或另一个嵌段组成。形成这些小域的规则有序图案是具有挑战性的，因为有序相通常表现出缺陷或与图案的偏差，其中聚合物链被捕获。研究人员建议在嵌段之间引入动态连接，这将允许一些嵌段共聚物与附近的嵌段共聚物交换它们的部分。研究人员假设，这种额外的自由度将使系统作为一个整体具有更大的灵活性，以实现不同相位的长程有序。这种更快的组装预计将减少加工时间、能源和浪费。研究人员计划通过与Girls Learning About Materials和Curie Camp@Illinois组织合作，将动态聚合物表征和分子模拟课程纳入日间夏令营项目。该提案旨在了解嵌段共聚物自组装中动态连接的影响。包括一小部分可交换键预计将增加链的流动性，提高长程有序性，并减少退火过程中的时间，能源和浪费。为了验证这一假设，研究人员将合成嵌段共聚物系统，包括永久和动态连接。聚苯乙烯和聚异戊二烯嵌段共聚物（PS-PI）和聚环氧乙烷和聚二甲基硅氧烷（PEO-PDMS）将在各种分子量下进行研究，使用小角X射线散射（SAXS）来评估形态。研究人员还将使用自洽场理论对该系统进行建模。研究人员还将探索额外的链在动态连接处的作用，通过建模和表征动态miktoarm星星聚合物，并与动态二嵌段共聚物进行对比，再次使用实验和计算方法。该项目的预期成果是深入了解动态对嵌段共聚物自组装的作用和减少动力学缺陷的机制。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。

Block copolymers are used in many applications such as epoxies, battery electrolytes, and elastic clothing, and are valued for their ability to combine two functions into one material. This ability comes from bonding two or more polymer chains made of different chemical units called monomers. The differing chemical monomers causes the different blocks of the polymer to separate, like oil and water. However, because they are bonded together, the result is small domains, consisting of one block or the other. Forming a regular, ordered pattern of these small domains is challenging as the ordered phases often exhibit defects, or deviations from the pattern, where the polymer chains become trapped. The investigators propose to introduce dynamic links between blocks that will allow some of the block copolymers to exchange their sections with a nearby block copolymer. The investigators hypothesize that this additional freedom will give the system as a whole greater flexibility to achieve long-range order of the different phases. This faster assembly is expected to reduce processing time, energy, and waste. The investigators plan to incorporate lessons about dynamic polymer characterization and molecular simulation into day-camp projects by partnering with the Girls Learning About Materials and the CURIE Camp@Illinois organizations.This proposal aims to understand the effects of dynamic junctions in block copolymer self-assembly. Including a fraction of exchangeable bonds is expected to increase chain mobility, improve long-range order and reduce time, energy and waste during the annealing process. To test this hypothesis, the investigators will synthesize block copolymer systems that include both permanent and dynamic junctions. Both polystyrene and polyisoprene block copolymers (PS-PI) and polyethylene oxide and polydimethylsiloxane (PEO-PDMS) will be studied at various molecular weights, using small angle x-ray scattering (SAXS) to assess the morphology. The investigators will also model this system using self-consistent field theory. The investigators will also explore the role of additional chains at a dynamic junction, by modeling and characterizing dynamic miktoarm star polymers and contrasting with dynamic diblock copolymers, again using both experimental and computational approaches. The expected outcome of this project are fundamental insights into the role of dynamic on block copolymer self-assembly and mechanisms to reduce kinetically trapped defects.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.