Stress-Dependent Multicolor Mechanochromism in Epoxy Thermosets Based on Rhodamine and Diaminodiphenylmethane Mechanophores
Stress-Dependent Multicolor Mechanochromism in Epoxy Thermosets Based on Rhodamine and Diaminodiphenylmethane Mechanophores
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基于罗丹明和二氨基二苯甲烷力团的环氧热固性材料中应力依赖性多色力致变色
DOI：
10.1021/acs.macromol.1c02242
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发表时间：
2022
期刊：
影响因子：
5.5
通讯作者：
Yuguo Ma
中科院分区：
文献类型：
--
作者：
Zhongtao Chen;Fangjun Ye;Tianyin Shao;Yeping Wu;Mao Chen;Yinyu Zhang;Xiuli Zhao;Bo Zou;Yuguo Ma
机械致变色聚合物在损伤报告和应力传感方面具有潜在的应用前景。尽管近年来取得了快速进展，但机械致色结构聚合物，如环氧热固性聚合物，仍然很难开发，更不用说通过视觉颜色变化来区分不同应力水平的结构材料了。这项工作提出了一类新的多色机械致变色环氧热固性材料，它可以通过结合两种不同的机械基团来区分低压应力和高压应力。氨基功能化罗丹明（Rh）是环氧热固性树脂的有效固化剂和比例应力传感器。环氧网络中的Rh机械团可以通过划伤或单轴压缩激活，显示可逆的颜色变化和红色荧光开启响应。通过将Rh机械载体与含有4,4 ' -二氨基二苯基甲烷（DDM）框架的商用环氧树脂结合，在单轴压缩和静水压力下实现了应力依赖的多色响应。在低压应力下形成的Rh两性离子使样品呈红色，而在高压应力下通过形成DDM的quinoidal methine形式使样品呈绿色。紫外可见光谱法证实了不同压应力下的不同活化。简单的制备和通过肉眼识别应力强度的能力使该策略适合于实际应用。
Mechanochromic polymers exhibit potential applications in damage reporting and stress sensing. Despite the rapid progress achieved in recent years, mechanochromic structural polymers, such as epoxy thermosets, remain difficult to develop, let alone structural materials that can distinguish different levels of stress by a visual color change. This work presents a new class of multicolor mechanochromic epoxy thermosets that can discriminate between low and high compressive stresses via the incorporation of two distinct mechanophores. Amino-functionalized rhodamine (Rh) moieties serve as efficient curing agents and ratiometric stress sensors for epoxy thermosets. The Rh mechanophore in the epoxy network can be activated either by scratch or uniaxial compression, showing a reversible color change and a red fluorescence turn-on response. A stress-dependent multicolor response under uniaxial compression and hydrostatic pressure is achieved by the combination of Rh mechanophores with a commercial epoxy resin containing a 4,4′-diaminodiphenylmethane (DDM) framework. The Rh zwitterion formed at a low compressive stress turns the sample red, while a high compressive stress turns the sample green via the formation of the quinoidal methine form of DDM. Differential activation under varying degrees of compressive stress is demonstrated by UV–vis spectroscopy. The facile preparation and ability to recognize stress intensity by the naked eye make this strategy suitable for practical applications.