CAREER: Using Three-Dimensional Confocal Rheology to Measure Shear Induced Microstructural Deformations in Colloidal Glasses

职业：使用三维共焦流变学测量胶体玻璃中剪切引起的微观结构变形

• 批准号: 0847490
• 负责人: Daniel Blair
• 金额: $ 52.5万
• 依托单位: Georgetown University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-03-01 至 2015-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0847490&HistoricalAwards=false
• 关键词: CAREER; Using; Three; Dimensional; Confocal

Non-Technical AbstractComplex fluids are fascinating materials with unique properties that arise from familiar constituents. For example, emulsions and foams such as salad dressing and seat cushions are comprised of simple materials such as liquid and air, yet their material properties remain topics of overwhelming interest. The goal of this Early Faculty CAREER Award is to gain a broader understanding of the glass transition by using emulsions -- a particularly interesting complex fluid. Emulsions are collections of very small liquid droplets, dispersed within another fluid, that closely mimic the behavior of atoms and molecules. However, due to their relatively large size, direct and real-time measurements of their positions and motions are obtainable in contrast to their atomic counterparts. The glass transition describes a transition in liquids that leads to their solidification when they are abruptly cooled. Rapid cooling forces the material to remain disordered while somehow becoming a solid. Remarkably, when these fluid droplets are tightly packed together, they undergo a transition where all of the droplets jam up, resulting in a material that is structurally very similar to window glass. By simultaneously deforming and imaging a glass comprised of emulsion droplets information about the mechanical properties, including the force on each droplet, can be directly measured. This information will provide key insights into the origins of the glass transition and will aid in the development of theoretical models that describe these complex materials. A major educational component initiated by the PI is the development of the Mid Atlantic Soft Matter Workshop (MASM). This workshop provides an ideal forum for researchers within the region whose interests reside at the interface of conventional disciplines. The workshop also naturally assists in the career advancement of young scientists by acquainting them with the local academic and industrial research community. Technical AbstractThe research in this Early Faculty CAREER Award is focused on developing the unique ability to precisely control and determine the mechanical properties within soft glassy solids at the bulk and microscopic scales. A system of colloidal suspensions (emulsions) is utilized to create materials that undergo kinetic arrest similar to the glass transition in a variety of condensed materials. What makes the experimental program described in this proposal unique is the development of methods to impose precise shear stresses during direct high speed three dimensional imaging. This technology will allow the system to be externally driven and measured (rheology) while simultaneously measuring the dynamic and structural evolution of the material at the microscale. To carry out this proposed research, two well established techniques for quantifying soft materials are combined; confocal microscopy and bulk rheology. From a broader perspective, measurements of the microstructure within colloidal glasses will allow for the development of microscopic theories of amorphous materials that will provide both practical and fundamental insights. A major outreach component initiated by the PI is the development of the Mid Atlantic Soft Matter Workshop (MASM). This workshop provides an ideal forum for researchers within the region whose interests reside at the interface of conventional disciplines. The workshop also naturally assists in the career advancement of young scientists by acquainting them with the local academic and industrial research community.

非技术摘要复杂流体是令人着迷的材料，具有由熟悉的成分产生的独特性质。例如，乳剂和泡沫，如沙拉酱和座垫，都是由液体和空气等简单材料组成，但它们的材料特性仍然是人们极感兴趣的话题。这个早期教师职业奖的目标是通过使用乳剂--一种特别有趣的复杂流体--来更广泛地了解玻璃化转变。乳状液是非常小的液滴的集合，分散在另一种流体中，非常接近于原子和分子的行为。然而，由于它们的尺寸相对较大，与它们的原子同行相比，可以直接和实时地测量它们的位置和运动。玻璃化转变描述了当液体突然冷却时导致其凝固的转变。快速冷却迫使材料保持无序，同时以某种方式变成固体。值得注意的是，当这些液滴紧密地堆积在一起时，它们会经历一个转变，所有的液滴都会堵塞，从而产生一种结构上非常类似于窗户玻璃的材料。通过同时对由乳液滴组成的玻璃进行变形和成像，可以直接测量有关机械性能的信息，包括对每个液滴的力。这些信息将为玻璃化转变的起源提供关键的见解，并将有助于开发描述这些复杂材料的理论模型。由国际和平研究所发起的一个主要教育组成部分是发展中大西洋软物质讲习班(MASM)。该讲习班为该区域内的研究人员提供了一个理想的论坛，这些研究人员的兴趣集中在传统学科的界面上。研讨会还通过让青年科学家熟悉当地的学术和工业研究社区，自然有助于他们在职业生涯中的进步。技术摘要这项早期教师职业奖的研究重点是开发独特的能力，在块状和微观尺度上精确控制和确定软玻璃固体的机械性能。胶体悬浮液(乳剂)系统被用来产生类似于各种凝聚材料中的玻璃化转变的动力学阻挡的材料。这项提案中描述的实验方案的独特之处在于开发了在直接高速三维成像过程中施加精确剪切应力的方法。这项技术将使系统能够在外部驱动和测量(流变学)，同时在微观尺度上测量材料的动态和结构演变。为了开展这项拟议的研究，结合了两种成熟的软材料量化技术：共聚焦显微镜和整体流变学。从更广泛的角度来看，测量胶体玻璃中的微结构将允许发展非晶态材料的微观理论，这将提供实用和基本的见解。国际和平倡议发起的一个主要外联部分是发展中大西洋软物质讲习班(MASM)。该讲习班为该区域内的研究人员提供了一个理想的论坛，这些研究人员的兴趣集中在传统学科的界面上。研讨会还通过让青年科学家熟悉当地的学术和工业研究社区，自然有助于他们在职业生涯中的进步。