Relaxation of Slow Glassy Interphases in Polymeric Systems

聚合物体系中慢玻璃态界面相的弛豫

基本信息

批准号：
2141221
负责人：
Sindee Simon
金额：
$ 58万
依托单位：
North Carolina State University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2021
资助国家：
美国
起止时间：
2021-08-15 至 2025-06-30
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2141221&HistoricalAwards=false
关键词：
Relaxation Slow Glassy Interphases Polymeric

项目摘要

NON-TECHNICAL SUMMARYThe glassy interphases in two model polymeric systems will be studied using two unique techniques: dilatometry to measure the volume and thermal expansion coefficient, and ultrafast calorimetry to measure the heat capacity and other important thermal properties. These complimentary techniques will be used to determine the size, properties, and dynamic behavior of the interphase in several nanostructured materials. For example, semicrystalline polymers will be studied since these materials consist of crystalline and non-crystalline domains. So will the nanoscale-size interphase between the two domains, whose properties are important for understanding the overall material behavior. Through characterization of this interphase the results of the research will provide a fundamental understanding of nanostructured materials for technological applications including but not limited to applications in structural composites and nano/microelectronics. The project includes the training of one graduate student, one postdoctoral researcher, and an undergraduate researcher in research in polymer physics, thermal analysis, behavior of interphases, and nanostructured materials. A strong effort will be made to include minority and female students. The project will include outreach to K-12 students, including organization of several one-week long materials modules for the TTU program "Science – It's a Girl Thing" for junior high school girls. TECHNICAL SUMMARYTwo model polymeric systems with slowly relaxing glassy interphases will be investigated, namely, the rigid amorphous fraction (RAF) in semicrystalline poly(ethylene terephthalate) (PET) and the immobile glassy layer at the particle interface in hairy polystyrene-grafted silica nanoparticles. The properties and relaxation dynamics of the glassy interphases will be studied as a function of morphology in the PET system and as a function of graft density, graft chain length, and silica content in the nanoparticle system. Dilatometry and nanocalorimetry experiments will aim to determine the length scale, glass transition temperature (Tg), and breadth of Tg for the rigid or "immobile" interphases, the temperature dependence of the segmental relaxation times associated with the rigid or "immobile" phases, and in the case of the semicrystalline polymer, the interplay and competition between structural recovery and crystallization as a function of material morphology. A unique temperature perturbation experiment will be implemented to allow structural recovery to be differentiated from crystallization in the semicrystalline system during isothermal aging experiments and to allow changes in the immobilized surface layer thickness to be quantified in the hairy nanoparticle system.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.

非技术总结将使用两种独特的技术研究两个模型聚合系统中的玻璃质相互重，以测量体积和热膨胀系数的扩张测定法，以及超快钙，以测量热容量和其他重要的热特性。这些免费技术将用于确定几种纳米结构材料中相间相间的大小，性质和动态行为。例如，由于这些材料由晶体和非晶体结构域组成，因此将研究半晶聚合物。这两个域之间的纳米级大小之间的相间将对理解总体材料行为很重要。通过表征该相间的研究结果将为技术应用提供纳米结构材料的基本理解，包括但不限于在结构组成和纳米/微电子中的应用。该项目包括对一名研究生，一名博士后研究员的培训以及聚合物物理学研究，热分析，相互作用的行为和纳米结构材料的研究生。将付出巨大的努力，包括少数民族和女学生。该项目将包括向K-12学生的宣传，包括针对初中女生的TTU计划“ Science - 这是一个女孩事物”的几个为期一周的材料模块。技术摘要模型的聚合物系统具有缓慢松弛的玻璃质相互作用，即，在半晶体替代（乙二醇乙二醇乙二醇乙酯）（PET）中的刚性无形分数（RAF）和粒料界面上的固定玻璃层的固定玻璃层中的刚性多乳玻璃层中的刚性无形分数（RAF）。玻璃质相互作用的特性和放松动力学将是宠物系统中形态的函数，并且是纳米粒子系统中移植密度，移植链长度和二氧化硅含量的函数。扩张学和纳米钙化实验的旨在确定刚性或“不动”相互作用的长度尺度，玻璃过渡温度（TG）和TG的宽度，TG的相互作用，与刚性或“不动”阶段相关的节段松弛时间的温度依赖性，以及在半层次范围内的构造和汇总的情况下，相互竞争和均应相互竞争。将实施一个独特的温度扰动实验，以允许在等热衰老实验期间与半结晶系统的结晶区分开结构性恢复，并允许在毛茸茸的纳米粒子系统中量化固定的表面层厚度的变化，这反映了NSF的法定任务和审查的良好范围，这是通过评估良好的范围来评估的。