de Castro Lucas D C, Lub Johan, Oliveira Osvaldo N, Schenning Albert P H J
São Carlos Institute of Physics, University of São Paulo, São Carlos, SP, 13560-970, Brazil.
Laboratory of Stimuli-responsive Functional Materials and Devices (SFD), Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, Eindhoven, The Netherlands.
Angew Chem Int Ed Engl. 2025 Jan 2;64(1):e202413559. doi: 10.1002/anie.202413559. Epub 2024 Oct 22.
Stimuli responsive optical materials are attractive for many areas, from healthcare to art design. However, creating intricate color-changing patterns for visual information is still a challenge. This work describes the preparation of mechanochromic structural colored intricate pictures imprinted in cholesteric liquid crystal elastomers by using a chiral isosorbide molecular photoswitch. The photoswitch contains a photoisomerizable cinnamate moiety and was incorporated in a main chain liquid crystal oligomer with photopolymerizable acrylate end groups. After coating, the structural colored film was irradiated with ultraviolet (UV) light in air causing E/Z isomerization of the cinnamate units leading to a redshift of the structural color of the film. A grayscale photomask was used to spatially control the photoisomerization reaction and imprint colorful pictures such as portraits and landscapes, in the cholesteric liquid crystal films with high resolution. Photopolymerization in a nitrogen atmosphere led to a mechanochromic cholesteric liquid crystal elastomer with striking structural colors that blueshift upon strain. The sharp details of the patterns were preserved even under deformation and the system returned to the initial state upon strain removal. Our work offers a simple photoswitch approach to prepare stimuli responsive optical polymers imprinted with color-changing pictures of unprecedented complexity.
刺激响应型光学材料在从医疗保健到艺术设计等众多领域都具有吸引力。然而，为视觉信息创建复杂的变色图案仍然是一项挑战。这项工作描述了通过使用手性异山梨醇分子光开关，在胆甾相液晶弹性体中印刻机械变色结构彩色复杂图案的制备方法。该光开关包含一个可光异构化的肉桂酸酯部分，并被并入具有可光聚合丙烯酸酯端基的主链液晶低聚物中。涂覆后，在空气中用紫外光照射结构彩色薄膜，导致肉桂酸酯单元发生E/Z异构化，从而使薄膜的结构颜色发生红移。使用灰度光掩模在空间上控制光异构化反应，并在胆甾相液晶薄膜中以高分辨率印刻如肖像和风景等彩色图片。在氮气气氛中进行光聚合反应，得到一种具有显著结构颜色的机械变色胆甾相液晶弹性体，该弹性体在应变时会发生蓝移。即使在变形情况下，图案的清晰细节也能得以保留，并且在去除应变后系统会恢复到初始状态。我们的工作提供了一种简单的光开关方法，用于制备印有前所未有的复杂变色图片的刺激响应型光学聚合物。
