SGER: Interfacial Tension-induced Deformations in Soft Solids

技术概述：双向形状记忆聚合物是能够响应于触发（例如温度变化）而在两种不同形状之间可逆地切换的材料。 我们提出了一个新的形状记忆概念的基础上，在交联聚合物共混物的各向异性两相形态的界面张力驱动的变形。 该项目将发展这种新的形状记忆概念的科学基础。 第一个目标是通过实验评估固体中的界面张力驱动变形是否足够大（应变~ 10%），以便在双向形状记忆应用中有用。 该项目的这一部分将在由悬浮在交联硅橡胶基质中的聚苯乙烯椭球体组成的模型实验系统上进行;将测量椭球体熔化引起的形状变化，作为椭球体纵横比和硅橡胶模量的函数。 第二个目标是进行数值有限元计算，计算形状变化的大小作为界面张力的函数，两相形态的尺寸尺度，和solid. The结果的solid.The结果将是一个明确的决定是否新的形状记忆概念有潜力的双向形状记忆应用。 非技术摘要：双向形状记忆聚合物是一种先进的材料，具有许多潜在的应用，从变形飞机到小型机械部件的机械驱动。 现有的双向形状记忆概念需要专门的聚合物。 我们提出了一个广泛推广的策略来设计双向形状记忆聚合物，该策略将允许使用广泛的聚合物对实现双向形状记忆。 本项目旨在评估这一想法的实际可行性。 如果这个探索性项目表明固体中的界面张力驱动变形足够大，我们将进行未来的研究，使用实用的聚合物实现新的形状记忆概念。 项目期间将培养一名博士后和一名本科生。 这项研究将促进与PI在机械工程和数学方面的同事的合作。

TECHNICAL SUMMARY:Two-way shape-memory polymers are materials that can reversibly switch between two different shapes in response to a trigger, such as change in temperature. We have proposed a new shape-memory concept based on interfacial tension-driven deformations in crosslinked polymer blends with an anisotropic two-phase morphology. This project will develop the scientific underpinnings of this new shape-memory concept. The first goal is to experimentally evaluate whether interfacial tension-driven deformations in solids are sufficiently large (strain ~ 10%) to be useful in two-way shape-memory applications. This portion of the project will be done on a model experimental system composed of polystyrene ellipsoids suspended in a crosslinked silicone rubber matrix; the shape change induced by melting the ellipsoids will be measured as a function of aspect ratio of the ellipsoids and the modulus of the silicone rubber. The second goal is to conduct numerical FEM calculations to calculate the magnitude of the shape change as a function of the interfacial tension, the size-scale of the two phase morphology, and the modulus of the solid.The result of this project will be an unambiguous determination of whether the new shape-memory concept has potential for two-way shape memory applications. NON-TECHNICAL SUMMARY:Two-way shape-memory polymers are advanced materials with numerous potential applications ranging from shape-morphing aircraft to mechanical actuation of parts of small machinery. Existing two-way shape-memory concepts require specialized polymers. We propose a broadly-generalizable strategy to design two-way shape-memory polymers, a strategy that will allow two-way shape memory to be realized using a wide range of polymer pairs. This project is intended to evaluate practical feasibility of this idea. If this exploratory project shows that interfacial tension-driven deformations in solids are sufficiently large, we will undertake future research to implement the new shape-memory concept using practical polymers. One post-doctoral fellow and one undergraduate will be trained during the project. The research will foster collaborations with the PI's colleagues in Mechanical Engineering and in Mathematics.