Investigating the Molecular Mechanisms of Thermally Active Amorphous Shape Memory Polymers

研究热活性非晶形状记忆聚合物的分子机制

• 批准号: 0758390
• 负责人: Thao Nguyen
• 金额: $ 24.91万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-04-15 至 2013-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0758390&HistoricalAwards=false
• 关键词: Investigating; Molecular; Mechanisms; Thermally; Active

Investigating the Molecular Mechanisms of Thermally Active Amorphous Shape Memory Polymers Thermally induced shape memory polymers are flexible smart materials that respond to a specific temperature event by generating a shape change. The molecular mechanism underpinning the behavior of amorphous shape memory polymers is the dramatic change in the mobility of the polymer chains induced by the glass transition. At high temperature, the chains are mobile and can rearrange, e.g., through rotation or diffusion of chain segments, to an equilibrium structure and stress state in response to a temperature change or applied load. The mobility vanishes as the polymer is cooled to below the glass transition temperature. This curtails structural and stress relaxation mechanisms allowing the material to store a temporary shape. Reheating to above the transition temperature restores the mobility allowing the material to relax and recover the permanent shape. The objectives of this proposal are: (1) to develop a fundamental understanding of the importance of the temperature-dependent structural and stress relaxation mechanisms on the performance of thermally induced shape memory polymers, and (2) to identify key thermomechanical parameters and quantify their effects on the shape memory performance. The fundamental understanding, and the modeling and computational tools, which will be developed, by this research has the potential to impact a broad range of technologies by reducing the design and manufacturing costs and enabling new and integrated functionalities. These technologies include multifunctional shape memory polymer medical devices, integrated sensors and actuators, and deployable aerospace structures. This project will benefit engineering education by integrating the research activities into fundamental engineering classes on mechanics of materials, and numerical methods. In addition, women and minorities will be recruited for the research activities to promote the participation of underrepresentative groups in the area of smart materials mechanics.

热致形状记忆聚合物是一种柔性的智能材料，在特定的温度条件下，聚合物的形状会发生变化。 支撑无定形形状记忆聚合物行为的分子机制是由玻璃化转变引起的聚合物链的迁移率的显著变化。在高温下，链是移动的并且可以重新排列，例如，通过链段的旋转或扩散，响应于温度变化或所施加的载荷而达到平衡结构和应力状态。当聚合物冷却至低于玻璃化转变温度时，迁移率消失。 这减少了结构和应力松弛机制，允许材料存储临时形状。 重新加热到高于转变温度恢复流动性，允许材料松弛并恢复永久形状。该提案的目标是：（1）发展的温度依赖性的结构和应力松弛机制的热致形状记忆聚合物的性能的重要性的基本理解，和（2）确定关键的热机械参数和量化它们的形状记忆性能的影响。本研究将开发的基本理解以及建模和计算工具有可能通过降低设计和制造成本并实现新的集成功能来影响广泛的技术。 这些技术包括多功能形状记忆聚合物医疗设备，集成传感器和执行器，以及可部署的航空航天结构。该项目将通过将研究活动整合到材料力学和数值方法的基础工程课程中，使工程教育受益。此外，还将招募妇女和少数民族参加研究活动，以促进代表性不足的群体参与智能材料力学领域。