Mechanochromic Displays Based on Photoswitchable Cholesteric Liquid Crystal Elastomers

Author(s)

de Castro, Lucas D. C. ; Lub, Johan ; Oliveira, Osvaldo N. ; Schenning, Albert P. H. J.

• Document type: Journal article
• Source: ANGEWANDTE CHEMIE-INTERNATIONAL EDITION; v. N/A, p. 7-pg., 2024-10-22.

Abstract

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. Mechanochromic intricate pictures with striking structural colors are imprinted in cholesteric liquid crystal elastomers by using a chiral isosorbide molecular photoswitch. image (AU)

• FAPESP's process: 18/22214-6 - Towards a convergence of technologies: from sensing and biosensing to information visualization and machine learning for data analysis in clinical diagnosis
• Grantee: Osvaldo Novais de Oliveira Junior
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 20/02938-0 - Coloured patterns based on bioinspired photonic crystals for mechanocromic applications
• Grantee: Lucas Daniel Chiba de Castro
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 22/13385-7 - Transferable stamp-like mechanochromic sensors for human motion monitoring assisted by image processing with machine learning models
• Grantee: Lucas Daniel Chiba de Castro
• Support Opportunities: Scholarships abroad - Research Internship - Post-doctor