UNS:Relaxation Dynamics of Particles and Polymers in Soft Glassy Suspensions

UNS：软玻璃态悬浮液中颗粒和聚合物的松弛动力学

• 批准号: 1512297
• 负责人: Lynden Archer
• 金额: $ 30万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1512297&HistoricalAwards=false
• 关键词: UNS; Relaxation; Dynamics; Particles; Polymers; UNS; Relaxation; Dynamics; Particles; Polymers

1512297(Archer)The goal of the proposed research is to study particle dynamics and relaxation in so-called soft glassy materials. Such materials are printable functional inks for additive manufacturing, fluids for batteries and fuel cells, and pharmaceutical formulations. Successful completion of this study could lead to the manufacturing of new types of fluids with properties tailored to specific engineering applications.It is proposed to develop a general framework for understanding how particle dynamics in jammed suspensions (nanoparticles in polymers) impact the transition from diffusive to hyperdiffusive dynamics. Recent reports on terminal relaxations in soft glasses have found that they are invariably and surprisingly hyperdiffusive. Hyperdiffusive relaxations are in fact now thought to be a characteristic of the soft glassy state and to reflect a material's out-of-equilibrium response to internal stresses, which are either built in at the glass transition or build up due to a variety of reasons. The PI and his group have recently discovered a class of soft glasses comprised of hairy nanoparticles that manifest a series of contradictory traits: (i) they are jammed and glassy; (ii) they manifest an accessible Newtonian flow regime and are able to reach equilibrium; (iii) they show little signs of aging; and (iv) they exhibit hyperdiffusive relaxations on long length and time scales. However, it is argued that the contradictory behavior is only superficial, and the dynamics of the system can reveal the fundamental behavior leading to these traits. They plan to use hairy nanoparticles as model systems, and a battery of experiments (photon correlation spectroscopies, small-angle X-ray scattering, mechanical rheometry, dielectric relaxation) and theory to shed light on the fundamental origins of hyperdiffusive relaxations in soft glasses. What makes this work exciting is that it goes after general models for dynamics of soft glasses, i.e., it looks to relate findings from experiments performed on limited time scales to dynamics in soft glasses on extended timescales. In addition to graduate education, plans to reach out to K-12 students and their teachers are laid out.

1512297（Archer）拟议的研究的目的是研究所谓的软玻璃材料中的颗粒动力学和放松。此类材料是可打印的功能墨水，用于添加剂制造，电池和燃料电池的流体以及制药配方。这项研究的成功完成可能会导致制造具有针对特定工程应用的特性的新型流体。它提议开发一个通用框架，以理解堵塞悬浮液中的粒子动力学如何影响从扩散到超罚款动力学的过渡。关于柔软眼镜的终末松弛的最新报道发现，它们总是过度过度的。实际上，过度延伸的放松现在被认为是柔软玻璃状状态的特征，并反映了材料对内部压力的不平衡反应，这要么是在玻璃过渡中内置的，要么由于多种原因而堆积。 Pi和他的小组最近发现了一类由毛茸茸的纳米颗粒组成的软眼镜，这些纳米颗粒表现出一系列矛盾的特征：（i）它们被堵塞和玻璃状； （ii）它们表现出一种可访问的牛顿流动状态，并能够达到平衡； （iii）他们几乎没有衰老的迹象； （iv）它们在长度和时间尺度上表现出过度的放松。但是，有人认为，矛盾的行为只是肤浅的，系统的动力学可以揭示导致这些特征的基本行为。他们计划使用毛茸茸的纳米颗粒作为模型系统，以及一系列实验（光子相关光谱，小角度X射线散射，机械流变体，介电弛豫）和理论，以阐明软眼镜中超延伸松弛的基本起源。这项工作令人兴奋的是，它追求了软眼镜动力学的通用模型，即，它似乎将在有限时间尺度上执行的实验的发现与扩展时间尺寸的软眼镜中的动力学相关联。除了研究生教育外，还计划与K-12学生及其老师联系。