Ishizuki Kuniaki, Takahashi Akira, Otsuka Hideyuki
Department of Chemical Science and Engineering, Institute of Science Tokyo, 2-12-1 Ookayama, Meguro-ku, Tokyo, 152-8550, Japan.
Research Center for Autonomous Systems Materialogy (AsMAT), Institute of Integrated Research, Institute of Science Tokyo, 4259 Nagatsuta-cho, Midori-ku, Yokohama, Kanagawa, Tokyo, 226-8501, Japan.
Macromol Rapid Commun. 2025 Apr;46(6):e2400812. doi: 10.1002/marc.202400812. Epub 2024 Dec 4.
Mechanochromic polymers can be used to visualize mechanical stimuli applied to materials. However, many of these polymers exhibit single-color mechanochromism, i.e., the polymer changes from its original color to another, thus potentially limiting the range of applications. Here, a versatile and readily accessible strategy for creating multicolor mechanochromic polymer blends that can detect whether a material is currently under stress or has already experienced stress is presented. The polymer blends are prepared by blending a segmented polyurethane and a polycaprolactone, each embedded with a radical-type mechanochromophore. These polymers appear either blue, pink, or green by stretching depending on the mechanochromophore employed. The introduction of different mechanochromophores into each of the segmented polyurethane and polycaprolactone polymers with different chain mobilities and the subsequent blending of these polymers affords a mechanochromic polymer blend that can be used to visually distinguish via a color change whether it is experiencing stress or has recently experienced stress. The colors observed under stress and after stress can be tuned as easily as mixing paint based on the combination of the mechanochromophores ("rainbow mechanochromism"). The strategy developed in this study can be expected to significantly advance the research of mechanochromic polymer materials.
机械变色聚合物可用于可视化施加于材料的机械刺激。然而，这些聚合物中的许多都表现出单色机械变色，即聚合物从其原始颜色变为另一种颜色，从而可能限制了应用范围。在此，提出了一种通用且易于实现的策略，用于制备多色机械变色聚合物共混物，该共混物能够检测材料当前是否处于应力状态或是否已经历过应力。该聚合物共混物是通过将一种嵌段聚氨酯和一种聚己内酯共混制备而成，每种聚合物都嵌入了一种自由基型机械变色团。通过拉伸，这些聚合物根据所采用的机械变色团呈现出蓝色、粉红色或绿色。将不同的机械变色团引入具有不同链迁移率的嵌段聚氨酯和聚己内酯聚合物中，随后将这些聚合物共混，得到一种机械变色聚合物共混物，可用于通过颜色变化直观地区分其是否正在经历应力或最近经历过应力。基于机械变色团的组合（“彩虹机械变色”），应力下和应力后的颜色观察结果可以像混合颜料一样轻松调节。预计本研究中开发的策略将显著推动机械变色聚合物材料的研究。
