Controlling the force range of polymeric force sensors made from rationally designed mechanochromic copolymer networks

这项提议涉及到一种新的概念，即具有可控力范围的机械变色聚合物材料的发展。基于非环二烯歧化聚合和二硫醇烯交联形成的主链螺吡喃弹性网络，我们将设计、合成和表征不同的材料，其中不同的应力水平会导致螺吡喃(SP，无色)-花菁(MC，有色)转变。这将通过改变取代基、聚合物链连接和玻璃化转变温度来实现，所有这些都改变了机械诱导的SP-MC异构化所需的活化能和机械转导的效果。为了更详细地理解这种异构化的基本原理，并指导合成，将并行进行密度泛函理论计算。一方面，这将使人们对机械诱导的SP-MC异构化有更深入的了解，另一方面也减少了合成功。使用原位光谱仪(UV-Vis、介电)进行力学实验，以演示新型弹性体上的力传感能力随施加的载荷的变化。该项目将克服限制机械变色反应在聚合力传感器中广泛应用的最关键的障碍之一。

This proposal is concerned with the development of a novel concept of mechanochromic polymeric materials exhibiting a controllable force range. Based on main chain spiropyran elastomeric networks made by acyclic diene metathesis polymerization and dithiol-ene cross-linking, we will design, synthesize and characterize different materials in which different levels of stress will cause the spiropyran (SP, colorless)-merocyanine (MC, colored) transformation. This will be enabled by varying substituents, polymer chain linkage, and glass transition temperature, all of which alter the activation energy needed for the mechanically-induced SP-MC isomerization and the efficacy of mechano-transduction. To understand the fundamentals of this isomerization in detail and to guide syntheses, density functional theory calculations will be carried out in parallel. On the one side this will lead to a deep understanding of the mechanically-induced SP-MC isomerization, and on the other side reduce the amount of synthetic work. Mechanical experiments with in-situ spectroscopies (UV-vis, dielectric) will be performed to demonstrate the force-sensing capabilities of on the novel elastomers as a function of the applied load. This project will overcome one of the most critical obstacles that limit a broader use of mechanochromic reactions in polymeric force sensors.