CAREER: Internal Structure and Properties of Confined Layer-by-Layer Films and Nanotubes

技术概要：层层组装（LbL）代表了一种新型和革命性的材料，其潜在应用范围从生物和能源系统到智能表面和传感器。然而，它们的内部结构和材料特性具有挑战性，因为它们通常超薄或局限于其基底。如许多中性聚合物所示，随着膜厚度的减小，材料性质（如玻璃化转变温度）显著偏离本体行为。这项工作的目的是（i）辨别不同厚度，曲率（以聚合物纳米管的形式）和组件使用量热法，椭圆偏振法和电化学的LBL组件内的物理和结构差异，以及（ii）将该信息与LBL膜如何生长和执行。将大块自支撑LbL膜与LbL涂覆的多孔模板进行比较。LbL厚度和孔径将分别变化以隔离限制和曲率的影响。聚合电解质在小孔内的组装和吸附也将探讨不同pH值和离子强度的水溶液。层的结构和性能的复合LBL膜含有纳米粒子将被比较那些没有确定硬无机材料内的一些层的影响。量热法将获得热波动，椭圆偏振法将获得与膜内相变相关的密度波动。电化学渗透性测量将定性地确定结构和自由体积内的膜使用氧化还原活性探针。总之，这些技术将提供新的知识，关于层混合，络合物，和限制LbL assemblies.Non-Technical摘要：层-层（LbL）组件代表了一个令人兴奋的新一类聚合物涂层和薄膜。LbL薄膜由带相反电荷的分子交替层制成，可应用于能量储存和生产，生物材料，自清洁表面等。然而，关于这些膜是否在给定温度下熔化、软化或交联知之甚少;这些知识对于辨别LbL组件是否商业化是重要的。在这个程序中，LbL薄膜和LbL纳米管的热性能将被确定。目的是了解厚度、曲率和组分如何影响薄膜结构和性能。如果成功的话，获得的知识可以用来操纵和设计用于有机能量存储和其他应用的薄膜。该计划的主要影响将是获取新知识和指导STEM学科的个人。参与者将学习最先进的表征和处理技术以及宝贵的专业技能。将资助一名研究生。社区外展计划通过在线视频演示，得克萨斯A M大学？德克萨斯州农工大学的高中教师E3课程？的妇女探索工程计划的年轻妇女，和其他出路。

TECHNICAL SUMMARY: Layer-by-layer (LbL) assemblies represent a novel and revolutionary class of materials with potential applications ranging from biological and energy systems to smart surfaces and sensors. However, their internal structure and materials properties are challenging to discern because they are often ultra thin or confined to their substrate. As shown for many neutral polymers, the materials properties (such as the glass transition temperature) significantly depart from bulk behavior as the film thickness deceases. The aim of this work is (i) to discern physical and structural differences within LbL assemblies of varying thickness, curvature (in the form of polymer nanotubes), and components using calorimetry, ellipsometry, and electrochemistry and (ii) to relate that information to how LbL films grow and perform. Bulk free-standing LbL films will be compared to LbL-coated porous templates. LbL thickness and pore diameter will be varied to isolate the influence of confinement and curvature, respectively. The assembly and adsorption of polyelectrolytes within small pores will also be explored for polyelectrolyte solutions of varying pH and ionic strength. Layer-structure and properties of composite LbL films containing nanoparticles will be compared to those without to determine the influence of hard inorganic materials within some of the layers. Calorimetry will access thermal fluctuations and ellipsometry will access density fluctuations related to phase transitions within the film. Electrochemical permeability measurements will qualitatively determine structure and free volume within the films using redox-active probes. Together, these techniques will give new knowledge regarding layer mixing, polyelectrolyte complexation, and confinement for LbL assemblies.NON-TECHNICAL SUMMARY: Layer-by-layer (LbL) assemblies represent an exciting new class of polymer coatings and films. Made from the alternating layers of oppositely charged molecules, LbL films have applications in energy storage and production, biomaterials, self-cleaning surfaces, and more. However, little is known regarding whether these films melt, soften, or crosslink at a given temperature; such knowledge is important to discern if LbL assemblies are to be commercialized. In this program, the thermal properties of LbL films and LbL nanotubes will be determined. The aim is to understand how thickness, curvature, and components influence film structure and properties. If successful, acquired knowledge could be used to manipulate and design thin films for organic energy storage and other applications. The major impact of this program would be in the acquisition of new knowledge and mentoring of individuals in STEM disciplines. Participants will learn state-of-the-art characterization and processing techniques as well as valuable professional skills. One graduate student will be supported. Community outreach is planned via online video demonstrations, Texas A&M University?s E3 program for high school teachers, Texas A&M University?s Women Explore Engineering program for young women, and other outlets.