Self-Healing Materials Enabled through Embedded Sensing and Stimulus Delivery

该奖项的研究目标是研究一种新形式的自主材料，这种材料可以感知损坏的存在，并使用刺激不仅可以治愈材料，还可以增强材料的韧性，防止损坏的传播。 该目的将通过合成光活化的形状记忆聚合物来实现，所述聚合物包含肉桂部分，当暴露于交替波长的光时，所述肉桂部分能够进行有效的光可逆环加成反应。 该可逆反应将用于主动裂解和改革共价交联以通过裂纹尖端处的局部模量变化来减轻损伤的传播，实现裂纹闭合的形状恢复，并最终跨越裂纹面改革交联以恢复材料的强度。光纤网络将被用来检测和信号的存在下的损害，同时提供一种机制，提供刺激直接到裂纹尖端。 形状记忆效应将提供一种恢复在裂纹前端处引起的塑性应变的手段，从而使材料返回到其原始几何形状，释放累积的应力并使裂纹面紧密接触以允许损伤的愈合。该奖项的更广泛影响集中在结构健康监测和自主系统之间的桥梁上，这些系统可以以可控和可重复的方式对损伤进行修复。 这包括与主机结构协调的传感器系统和信号调节硬件的设计，而不是目前使用的临时部署。 此外，这项研究将影响光响应聚合物的现状，使其能够整合到一系列新的应用中。 教育部分的目标是使用生物启发系统和智能材料的概念来展示现代工程的多学科特征，并刺激学生的教育成长。

The research objective of this award is to study a new form of autonomous material that senses the presence of damage and use stimulus to not only heal the material but to toughen it against the propagation of damage. This objective will be accomplished through the synthesis of light activated shape memory polymers that incorporate cinnamic moieties, which are able to undergo efficient photoreversible cycloaddition reactions when exposed to alternating wavelengths of light. This reversible reaction will be used to actively cleave and reform covalent crosslinks to mitigate the propagation of damage though local modulus changes at the crack tip, achieve shape recovery for crack closure and to ultimately reform crosslinks across the crack face to recover the strength of the material. A fiber optic network will be employed to detect and signal the presence of damage while providing a mechanism to deliver stimulus directly to the crack tip. The shape memory effect will provide a means to recover the plastic strain induced at the crack front thus returning the material to its original geometry, relaxing built up stresses and bringing the crack faces into intimate contact to allow healing of the damage. The broader impacts of this award focus on the bridging of structural health monitoring and autonomous systems that can react to heal damage in a controlled and repeatable manner. This includes the design of sensor systems and signal conditioning hardware in coordination with the host structure rather than the ad hoc deployment currently used. Furthermore, this research will impact the current state in photoresponsive polymers allowing their integration into a range of new applications. The goal of the education component is to use the concept of biologically inspired systems and smart materials to demonstrate the multidisciplinary character of modern engineering and to stimulate the educational growth of students.