CAREER: Formation of Stable Polymer Glasses

技术概要：玻璃的性质在很大程度上取决于玻璃形成的途径。 低能量、超稳定的有机分子玻璃可以通过物理气相沉积形成。 这种生产超稳定玻璃的途径不适用于聚合物。 因此，低能量、超稳定的聚合物玻璃的形成尚未实现。 该职业奖的第一个目标是探索基质辅助脉冲激光蒸发（MAPLE）作为生产低能量，超稳定聚合物薄膜的途径。 待探索的处理参数包括生长速率（瞬时和平均）、衬底温度和沉积分子的动能。 将对所有薄膜的稳定性、形态和机械性能进行表征。 本职业生涯的第二个目标是探索稳定玻璃形成的机制。在这里，提出了新的实验来探索稳定的玻璃形成和表面流动性之间的关系。首先，将比较表现出不同增强的表面迁移率的聚合物玻璃的稳定性。 其次，将比较以不同表面积/体积比形成的聚合物膜的稳定性。 第三，将开发一种独特的荧光多层方法，该方法将允许直接测量自由表面稳定性和能量景观表面。 这项提案将解决的基本问题包括：具有更大表面流动性的薄膜是否形成更稳定的玻璃？表面分子能探索低能态吗？ 非技术性总结：这项工作解决了有关低能量，稳定的玻璃形成的基本问题，最终，这项工作可能有一天为开发具有无与伦比的热稳定性和动力学稳定性的聚合物玻璃提供指导。 该提议将探索稳定的聚合物玻璃作为超屏障膜的一种可能的应用。 这些材料的其他潜在应用包括1）基于有机发光二极管技术的显示器，其对环境因素（例如，湿度、温度波动）和更低的功耗，2）具有更大形态稳定性的有机电子器件，和3）对污染物表现出更大抗性的涂层和保护性表层。新发现的低能量，稳定的玻璃将被纳入一个新的本科生/研究生选修课程的玻璃化转变。 拟议的研究将由高中，本科和研究生组成的多元化团队完成。 这个职业奖概述了一个独特的4级教育和推广计划，以增加代表性不足的少数民族和来自经济上处于不利地位的学生对科学感兴趣的数量，获得STEM学位，并参与学术研究。 该推广计划旨在促进科学职业道路的各级科学参与。

TECHNICAL SUMMARY: The properties of glasses strongly depend on the path to glass formation. Low energy, ultra-stable organic molecular glasses can be formed by physical vapor deposition. This route to producing ultra-stable glasses is not amenable to polymers. As such, the formation of low energy, ultra-stable polymer glasses have not been realized. The first objective of this CAREER award is to explore Matrix Assisted Pulsed Laser Evaporation (MAPLE) as a route to produce low-energy, ultra-stable polymer films. Processing parameters to be explored include growth rate (both instantaneous and average), substrate temperature, and kinetic energy of the depositing molecule. The stability, morphology, and mechanical properties will be characterized for all films. The second objective of this CAREER is to explore the mechanism of stable glass formation. Here, new experiments are proposed to explore the relationship between stable glass formation and surface mobility. First, the stability of polymer glasses that exhibit different enhanced surface mobility will be compared. Second, the stability of polymer films formed with different surface area/volume ratios will be compared. Third, a unique fluorescence multilayer approach that will allow for the direct measurement of free surface stability and energy-landscape surface will be developed. Fundamental questions this proposal will address include: Do films with greater surface mobility form more stable glasses? Are surface molecules able to explore lower energy states? NON-TECHNICAL SUMMARY: The work addresses fundamental questions concerning low-energy, stable glass formation, and, ultimately, the work may someday provide guidelines for the development of polymer glasses with unmatched thermal and kinetic stability. This proposal will explore one possible application of stable polymer glasses as ultra-barrier membranes. Other potential applications of these materials include 1) displays based on organic light-emitting diode technology, possessing enhanced stability to environmental factors (e.g., humidity, temperature fluctuations), and lower power consumption, 2) organic electronics with greater morphological stability, and 3) coatings and protective skin layers exhibiting greater resistance to contaminants. The new discovery of low energy, stable glasses will be incorporated into a new undergraduate/graduate elective course on the glass transition. The proposed research will be accomplished by a diverse team of high school, undergraduate and graduate students. This CAREER award outlines a unique 4-tier educational and outreach program to increase the number of underrepresented minorities and students from economically disadvantaged backgrounds interested in science, obtaining STEM degrees, and participating in academic research. The outreach program is designed to promote scientific involvement at all levels of a scientific career path.