Viscoelastic Response of Ultrathin Polymer Films: Bubble Inflation, Liquid Dewetting and Molecular Architecture Effects

超薄聚合物薄膜的粘弹性响应：气泡膨胀、液体反润湿和分子结构效应

• 批准号: 1207070
• 负责人: Gregory McKenna
• 金额: $ 37.5万
• 依托单位: Texas Tech University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-05-01 至 2016-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1207070&HistoricalAwards=false
• 关键词: Viscoelastic; Response; Ultrathin; Polymer; Films

TECHNICAL SUMMARY: The work is a fundamental investigation of the viscoelastic response of ultrathin polymer films in two different conditions. The work will compare, contrast, and seek origins of differences between the nanobubble inflation method developed by the PI at Texas Tech University and the liquid dewetting method developed by Bodiguel and Fretigny in Paris (which are the only methods currently available to measure the viscoelastic response of unsupported films). The two techniques had shown substantial differences in glass transition temperatures as functions of film thickness. The two methods differ in that one measures films with free surfaces and the other measures films floating on a mobile substrate. The planned research will examine the effects of changing substrate, molecular weight, and molecular architecture on the viscoelastic properties of ultrathin polymer films. It will explore the hypothesis that the relevant differences in confinement behavior are related to very subtle differences in surface energy/surface interactions and will provide new data focused on the understanding of how surfaces and interfaces impact the dynamics of polymers confined to the nanometer size scale.NON-TECHNICAL SUMMARY: The dramatic influence of nanoscale confinement on material behavior is exemplified by the response of ultrathin polymer films that show tremendous property changes, for example, in freely suspended films having nanometer thicknesses. Yet the origins of these changes are not yet elucidated. The present work probes these changes using two novel nanomechanical test methods. The work compares and contrasts mechanical properties of a series of polymers having different molecular characteristics. In addition, because there is such a strong apparent effect of the environment seen by the film surface, the work probes the behavior of the ultrathin polymer films exposed to liquids having different properties. The research provides new data in the understanding of how surfaces and interfaces impact the mechanics of polymers confined to the nanometer size scale. The project also has an important component that trains graduate students and, in addition to their scientific training, involves them in a STEM outreach program to young girls through the "Science: It's a Girl Thing" Program at Texas Tech University.

技术概述：这项工作是超薄聚合物薄膜在两种不同条件下粘弹性响应的基础研究。这项工作将比较、对比和寻找德克萨斯理工大学PI开发的纳米气泡膨胀方法与巴黎Bodiguel和Fretigny开发的液体脱湿方法（这是目前唯一可用的测量无支撑薄膜粘弹性响应的方法）之间差异的来源。这两种技术显示出玻璃化转变温度随薄膜厚度的变化有很大差异。这两种方法的不同之处在于，一种测量具有自由表面的薄膜，另一种测量漂浮在移动基板上的薄膜。计划中的研究将检查改变衬底、分子量和分子结构对超薄聚合物薄膜粘弹性性能的影响。它将探讨约束行为的相关差异与表面能/表面相互作用的非常微妙的差异有关的假设，并将提供新的数据，专注于理解表面和界面如何影响纳米尺度下聚合物的动力学。非技术概述：纳米尺度约束对材料行为的巨大影响体现在超薄聚合物薄膜的响应上，其表现出巨大的性能变化，例如，具有纳米厚度的自由悬浮薄膜。然而，这些变化的起源尚未阐明。本文采用两种新颖的纳米力学测试方法来探讨这些变化。该工作比较和对比了一系列具有不同分子特征的聚合物的机械性能。此外，由于薄膜表面所看到的环境有很强的明显影响，因此本研究探讨了超薄聚合物薄膜在不同性质液体中的行为。该研究为理解表面和界面如何影响纳米尺度聚合物的力学提供了新的数据。该项目还有一个重要组成部分，即培训研究生，除了对他们进行科学培训外，还包括通过德克萨斯理工大学（Texas Tech University）的“科学：这是女孩的事情”（Science: It's a Girl Thing）项目，让他们参加一个面向年轻女孩的STEM推广项目。