In-Plane Nanostructural Organization of Copolymer Molecules along Polymer/Polymer Interfaces

CBET-0756711 Spontak沿着聚合物/聚合物界面的共聚物分子的面内纳米结构组织对于高级涂料的开发至关重要，在这种情况下，必须完全建立和理解负责促进膜稳定的分子尺度条件。这种性质的大多数研究认为界面是横向均匀的，特别是在很长的时间。然而，PI最近发现，将不相容的嵌段共聚物或核-壳聚合物纳米颗粒添加到薄膜层压材料中会引起沿聚合物/聚合物界面的离散不均匀性沿着，从而表明横向界面结构化在相容化/稳定化中起重要作用。先前的结果（i）提出了关于共聚物自组织或纳米颗粒聚集和界面结构作为功能之间的竞争的基本问题，和（ii）为涂层和模板技术的薄膜聚合物层压板开辟了新的途径。长期目标是：（1）了解二嵌段共聚物在两种不混溶均聚物界面处的横向结构的类型和程度，以及横向界面结构是如何形成的。虽然大多数以前的研究集中在探索共聚物结构正常的两个不混溶的均聚物之间的界面，他们以前的结果表明，这种结构可以是高度不均匀的。在薄膜层压体中，这种界面不均匀性可能不利地影响薄膜稳定性。共聚物分子沿着界面的面内结构变化提供了离散的横向界面结构的实验证据，并值得深入研究。（2.）利用观察到的现象作为大面积组装和聚合物表面图案化的可控手段。PI已经观察到CSP纳米颗粒优先分离到聚合物/聚合物界面，并且它们从膜中突出的程度敏感地取决于表面/界面能。这些CSP纳米颗粒的开/关位置，由表面能的变化触发，以及同时组织的平面内结构的能力，将使这种系统成为有源反射表面和智能标签的方便候选者。需要更好地理解控制界面结构的材料和环境因素。（3.）询问嵌段共聚物和CSP纳米粒子在两种不混溶聚合物之间的界面处的时空组织，以获得设计有效界面增强剂和相容剂的有价值的指导。虽然嵌段共聚物被广泛确立为大分子表面活性剂，但对远离平衡的增强机制的早期阶段知之甚少。PI过去的实验表明，嵌段共聚物分子或CSP纳米颗粒在界面处的组织不能被视为简单的“1D”问题，因为存在离散的面内特征。了解这种结构的时空行为是至关重要的，在确定相关的聚合物体系（共混物和薄膜）的增容的最佳条件。该项目将导致一名研究生接受培训，以（i）使用最先进的分析方法来研究薄膜聚合物层压材料，（ii）开发设计和解决问题的技能，以可重复，有意义和有见地的方式生成和分析本提案中概述的多组分系统。作为他/她的研究生课程的一部分，学生将被要求提供两个演示更新/学期，以提高他/她的沟通和演讲技巧，为会议做准备。PI目前正在北卡罗来纳州立工程学院内启动一个国际本科高级设计项目，并将邀请国际学生团队参与该项目。参与该项目的学生将与位于北卡罗来纳州百年校园的百年中学的学生密切合作。最后，PI和co-PI都被选中，在全校范围内的竞争的基础上，作为本科贝克曼学者的导师，因此研究将得到充分支持，本科研究助理。将通过传统方式传播在该项目过程中产生的学术成果，如在科学会议上口头/海报介绍和在影响力大的科学期刊上发表。这项研究的结果将被列入两个研究生课程共混物和界面。

CBET-0756711SpontakThe In-Plane Nanostructural Organization of Copolymer Molecules along Polymer / Polymer Interfaces is critical to the development of advanced coatings, in which case the molecular-scale conditions responsible for promoting film stabilization must be fully established and understood. Most studies of this nature consider the interfaces to be laterally homogeneous, especially at long times. The PIs have recently found, however, that addition of an incompatible block copolymer or a core-shell polymer nanoparticle to a thin-film laminate induces discrete heterogeneities along the polymer / polymer interface, thereby indicating that lateral interfacial structuring plays an important role in compatibilization / stabilization. Previous results (i) raise fundamental questions regarding the competition between copolymer self-organization or nanoparticle aggregation and interfacial structuring as functions, and (ii) open new avenues to thin-film polymer laminates for coating and templating technologies. The long range objectives are to: (1.) Understand the type and extent of lateral structuring of diblock copolymers at interfaces between two immiscible homopolymers and how lateral interfacial structuring develops. While most previous studies have concentrated on exploring copolymer structure normal to the interface between two immiscible homopolymers, their previous results demonstrate that such structuring can be highly heterogeneous. In a thin-film laminate, such interfacial heterogeneities may adversely affect thin-film stability. The in-plane structure variations of copolymer molecules along the interface provide experimental evidence of discrete lateral interfacial structuring and warrant in-depth examination. (2.) Utilize the observed phenomena as a controllable means of large-area assembly and patterning of polymer surfaces. The PIs have observed that CSP nanoparticles preferentially segregate to polymer / polymer interfaces, and the extent to which they protrude from the film depends sensitively on the Surface / interfacial energy. The ON/OFF position of these CSP nanoparticles, triggered by a change in surface energy, and the simultaneous capability of organized in-plane structure would make such system convenient candidates for active reflective surfaces and smart tags. An improved understanding of the material and environmental factors governing interfacial structuring is needed. (3.) Interrogate the spatiotemporal organization of block copolymers and CSP nanoparticles at interfaces between two immiscible polymers to acquire valuable guidance in designing efficient interfacial reinforcing and compatibilizing agents. While block copolymers are widely established as macromolecular surfactants, little is known about the early stages of the reinforcing mechanism, far from equilibrium. The PIs past experiments show that the organization of block copolymer molecules or CSP nanoparticles at interfaces cannot be perceived as a simple '1D" problem since discrete in-plane features exist. Understanding the spatiotemporal behavior of such structure is crucial in identifying optimal conditions for compatibilization in relevant polymer systems (blends and thin films). This project will result in a graduate student being trained to (i) use state-of-the-art analytical methods to investigate thin-film polymer laminates and (ii) develop design and problem-solving skills to generate and analyze, in reproducible, meaningful and insightful fashion, the multicomponent systems outlined in this proposal. As part of his/her graduate program, the student will be required to give two presentation Updates / semester to improve his/her communication and presentation skills in preparation for conference meetings. The PI is currently initiating an international undergraduate senior design program within the NC State College of Engineering and will involve international student teams with this project. The student involved in this project will work closely with students at the Centennial Middle School located on the NC State Centennial Campus for this purpose. Lastly, the PI and co-PI have both been selected, on the basis of a University-wide competition, as mentors for undergraduate Beckman Scholars, and so the research will be augmented with a fully supported, undergraduate research assistant. The scholarly results generated during the course of this project will be disseminated through traditional modes, such as oral/poster presentations at scientific meetings and publication in high-impact scientific journals. Results from this research will be included in two graduate-level courses on blends and interfaces.