Confinement in Electrospun Polymer-Based Nanocomposites, with Research Opportunities for Deaf and Hard of Hearing Interns

技术总结：使用静电纺丝（ES）技术加工纳米级纤维，将研究限制对基本物理和结构特性的影响。限制是指通过在纤维内部添加固定屏障而对聚合物链的移动性产生的限制。 除了聚合物的晶体之外，添加剂如碳纳米管、有机改性的硅酸盐或二氧化硅导致纳米复合材料的形成，其中这些纳米填料也用作导致链限制的固定屏障。纳米复合材料的弛豫性能被改变，导致性能的有益改善，例如使用温度的提高和机械模量的提高。 ES聚合物基纳米复合材料的相结构和物理性能将被研究，因为它们与纤维取向，结晶度，填料类型和量有关。 目标是：1.提供关于晶体或纳米填料与半结晶电纺纳米复合纤维的非结晶部分之间的关系的基本理解，特别是通过准等温热容分析和快速扫描芯片量热法的新方法; 2.将纤维性质（例如，直径、结晶度、链取向、填料类型、量和分散度）与约束程度的关系;和3.将填充物的约束效应与晶体的约束效应分开。 工作中使用的技术包括通过温度调制差示扫描量热法进行高精度、高精度热容测量，以量化限制水平。 第一次，ES纤维上的快速扫描芯片量热技术（通过与罗斯托克，德国的Schick组的国际合作）将被应用于研究ES纤维中的均匀成核。 此外，介电弛豫谱（DRS）将首次用于表征ES纤维的偶极弛豫。 这些研究将提供一个知识基础，这将提高ES纤维材料在技术重要领域的使用，如非织造织物，再生医学，运输和催化。非技术总结：非织造膜将使用非常小的直径纤维，在纳米尺度上，通过施加高电场到含有聚合物和添加剂（如碳纳米管或粘土）的溶液中。 与传统的大直径纤维相比，以这种方式形成的纳米纤维更坚固且更耐热。 加工条件和添加剂的性质将有所不同，以查看哪种组合产生具有最佳性能的纳米纤维。 这些非织造织物是用作过滤膜、催化剂、药物递送以及作为智能服装材料的组分的候选材料。 已经建立了国家和国际合作，使用专业设备和新的加工条件进行这项研究。 为残疾学生提供研究机会，四名聋人和重听本科生将参加实习，并在夏季进行该项目的研究。 这些实习生将学习制作非织造纳米纤维，对其进行热处理，并研究其物理特性。

TECHNICAL SUMMARY:Using the electrospinning (ES) technique for processing nano-scale fibers, the effect of confinement on fundamental physical and structural properties will be investigated. Confinement refers to restrictions on the mobility of the polymer chains brought about by addition of fixed barriers inside the fibers. Besides the crystals of the polymer, additives such as carbon nanotubes, organically modified silicates, or silica, lead to formation of nanocomposites in which these nanofillers also serve as fixed barriers leading to chain confinement. The relaxation properties of the nanocomposite are altered, leading to beneficial improvement of properties, for example an increase in the use temperature, and an increase in the mechanical modulus. The phase structure and physical properties of ES polymer-based nanocomposites will be studied as they relate to the fiber orientation, degree of crystallinity, filler type, and amount. The objectives are to: 1. Provide fundamental understanding about the relationship between crystals or nanofillers and the non-crystalline portions of the semicrystalline electrospun nanocomposite fibers, especially through new methods of quasi-isothermal heat capacity analysis and fast scanning chip calorimetry; 2. Correlate the fiber properties (e.g., diameter, crystallinity, chain orientation, filler type, amount, and dispersion) to the degree of constraint; and 3. Separate the confining effects of the filler from those of the crystals. Techniques to be used in the work include high precision, high accuracy heat capacity measurements by temperature modulated differential scanning calorimetry to quantify the level of confinement. For the first time, the techniques of fast scanning chip calorimetry on ES fibers (through international collaboration with the Schick group in Rostock, Germany) will be applied to study homogeneous nucleation in ES fibers. Also for the first time, dielectric relaxation spectroscopy (DRS) will be used to characterize the dipolar relaxations of ES fibers. These studies will provide a knowledge base which will enhance the use of ES fiber materials in technologically important areas such as non-woven textiles, regenerative medicine, and transport and catalysis.NON-TECHNICAL SUMMARY:Non-woven membranes will be created using very small diameter fibers, on the nano-scale, by applying a high electric field to a solution containing polymer and additives (such as carbon nanotubes or clay). Nanofibers formed this way are stronger and more heat resistant compared to conventional large diameter fibers. The processing conditions and nature of the additive will be varied to see which combinations yield nanofibers with the best properties. These non-woven fabrics are candidate materials for use as filtration membranes, in catalysis, for drug delivery, and as a component of smart clothing materials. Both national and international collaborations have been established for conducting this research using specialty equipment and novel processing conditions. To provide research opportunities for students with disabilities, four deaf and hard of hearing undergraduate students will participate in an internship, and perform research on the project during the summer months. These interns will learn to make the non-woven nanofibers, heat treat them, and study their physical properties.