Size Dependent Mechanical Properties for Elastic Polymer Gels

弹性聚合物凝胶的尺寸依赖性机械性能

• 批准号: 1304724
• 负责人: Alfred Crosby
• 金额: $ 42万
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-06-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1304724&HistoricalAwards=false
• 关键词: Size; Dependent; Mechanical; Properties; Elastic

TECHNICAL SUMMARY:This project, supported by the Polymers Program of the Division of Materials Research and the Mechanics of Materials Program of the Division of Civil, Mechanical, and Manufacturing Innovation, will develop fundamental knowledge of mechanical properties for ultra-soft materials. The primary goal will be to experimentally investigate the effect of size scale on achieving large strain, resilient mechanical responses in ultra-soft materials. Ultra-soft materials with these attributes are important for numerous applications, from protective devices to tissue engineering. Recently, many novel polymers which mimic naturally-occurring gels, such as resilin, have been demonstrated with some success, but these polymers are often complex and potentially difficult to implement practically. An alternative strategy may be found by understanding the mechanical properties of ultra-soft materials at small size scales. This strategy is motivated by a well-known property for metals and ceramics that size can influence the sensitivity to defects under mechanical loading. Thus, metals and ceramics fabricated on small size scales can display extraordinary mechanical properties. For ultra-soft materials, these effects have not been experimentally measured. In the proposed research, scaling relationships provide guiding hypotheses that predict the existence of optimized size scales for large strain reversible deformations for swollen polymer networks. These hypotheses will be experimentally confirmed using standard and novel characterization methods on two different gel materials. The results of this research will lead to new characterization methods and understanding for both synthetic gels and living tissues, as well as new materials strategies for creating ultra-soft materials that can achieve high strains, high strength, and high resiliency.NON-TECHNICAL SUMMARY:Ultra-soft materials are attractive for many technologies, from protective gear to tissue engineering. Currently, these materials are either brittle, not allowing them to stretch very far, or they are able to stretch far by dissipating energy, similar to the way Silly Putty works. Recent efforts have focused on creating new polymers that mimic the structure and properties of biological proteins, such as resilin. However, these new materials are complex and may be difficult to implement practically. One possible strategy for overcoming these challenges is to take advantage of predicted mechanical property enhancements at small size scales. It is well known that metals and ceramics display improved mechanical performance on small size scales relative to their molecular size scale; however, similar experimental investigations have not been conducted on ultra-soft materials. The proposed research will experimentally investigate the mechanical properties of ultra-soft materials at small sizes to achieve high strains, high strength, and high resiliency. The lessons learned are anticipated to impact the development of new protective devices; to influence the characterization for soft materials including living tissues; and to provoke new questions related to traumatic damage in soft biological tissues, such as the brain. In addition, an innovative workshop program on Bioinspired Materials Design will be developed to inspire high school students from diverse backgrounds to pursue future careers in science and engineering. This program will allow students and the general public in Western Massachusetts to realize the importance of materials and mechanics research, the role of creativity in scientific and engineering discovery, and the difficulties that arise when bioinspiration is used without foundational principles.

技术摘要：该项目得到材料研究部聚合物项目和土木、机械和制造创新部材料力学项目的支持，将开发超软材料机械性能的基础知识。主要目标是通过实验研究尺寸尺度对超软材料中实现大应变、弹性机械响应的影响。 具有这些属性的超软材料对于从防护装置到组织工程的众多应用都很重要。 最近，许多模仿天然凝胶的新型聚合物（例如节肢弹性蛋白）已被证明取得了一些成功，但这些聚合物通常很复杂，并且可能难以实际实施。通过了解小尺寸超软材料的机械性能，可以找到替代策略。 这一策略的动机是金属和陶瓷的一个众所周知的特性，即尺寸会影响机械负载下对缺陷的敏感性。 因此，小尺寸制造的金属和陶瓷可以表现出非凡的机械性能。 对于超软材料，这些影响尚未通过实验测量。在所提出的研究中，尺度关系提供了指导假设，预测膨胀聚合物网络大应变可逆变形的优化尺寸尺度的存在。 这些假设将通过使用标准和新颖的表征方法对两种不同的凝胶材料进行实验证实。这项研究的结果将带来对合成凝胶和活组织的新表征方法和理解，以及创建可实现高应变、高强度和高弹性的超软材料的新材料策略。 非技术摘要：超软材料对许多技术都有吸引力，从防护装备到组织工程。 目前，这些材料要么是脆性的，不允许它们拉伸很远，要么它们能够通过耗散能量来拉伸很远，类似于橡皮泥的工作方式。 最近的努力集中在创造模仿生物蛋白质（例如节肢弹性蛋白）的结构和特性的新型聚合物。 然而，这些新材料很复杂，可能难以实际实施。 克服这些挑战的一种可能策略是利用小尺寸尺度上预测的机械性能增强。 众所周知，金属和陶瓷在相对于其分子尺寸尺度的小尺寸尺度上表现出改进的机械性能；然而，尚未对超软材料进行类似的实验研究。 拟议的研究将通过实验研究小尺寸超软材料的机械性能，以实现高应变、高强度和高弹性。预计吸取的经验教训将影响新保护装置的开发；影响包括活体组织在内的软材料的表征；并提出与软生物组织（例如大脑）创伤性损伤有关的新问题。 此外，还将开发一个关于仿生材料设计的创新研讨会计划，以激励来自不同背景的高中生追求未来的科学和工程职业。该项目将使马萨诸塞州西部的学生和公众认识到材料和力学研究的重要性、创造力在科学和工程发现中的作用，以及在没有基本原理的情况下使用生物灵感时出现的困难。