Stimuli-Responsive Ionic Liquid Crystals as Promising Tailor-Made Materials
Andreia F. M. SANTOS1, Maria H. GODINHO2, J. L. FIGUEIRINHAS3, Madalena DIONÍSIO1, Luis C. BRANCO1
1LAQV-REQUIMTE, Department of Chemistry, NOVA School of Science and Technology, NOVA University of Lisbon, Campus de Caparica, Caparica, Portugal
2i3N/CENIMAT, Department of Materials Science, NOVA School of Science and Technology, NOVA University of Lisbon, Campus de Caparica, Caparica, Portugal
3CeFEMA and Department of Physics, Instituto Superior Técnico, University of Lisbon, Av. Rovisco Pais, 1, Lisbon, Portugal
Smart materials are known for their ability to stimuli-responsive environmental variations, usually reversibly, by the activation of material’s specific functions [1]. In particular, chromogenic materials are capable of changing their coloration when induced by light, electrical potential, temperature, pressure or pH variations, originating, respectively, photo-, electro-, thermo-, piezo- and halochromic responses [2]. It has been proven that materials exhibiting liquid crystalline characteristics, i.e., anisotropy, optical birefringence, anisotropic electrical and magnetic properties, fluidity and the inability to support shear, are prone to enhance the performance of a certain material [3]. In this context, motivated by the possibility to design unique ionic liquids, this work aims to combine the advantages of ionic liquids with liquid crystals to develop new functional ionic liquid crystals (ILCs). Several pyridinium bromides and n-methylpyridinium (n = 2, 3 or 4) bromides were synthesized through sustainable methods and their mesomorphic behaviour was firstly evaluated [4]. The two most promising ionic liquid crystals were used as intrinsically chromogenic materials as well as a task-specific media to dissolve responsive probes. Herein, we present the synthesis, characterization and application of novel photo-, thermo- and solvatochromic ILCs.
Acknowledgments: This work was supported by the Associate Laboratory for Green Chemistry LAQV (UID/QUI/50006/2019), i3N (UID/CTM/50025/2019) and CeFEMAS (UID/CTM/04540/2019), which are financed by national funds from FCT-MCTES and by FEDER funds through the COMPETE 2020 Program. The authors also thank the National Funds through FCT-MCTES and POR Lisboa 2020, under the projects numbers POCI-01-0145-FEDER-007688, PTDC/CTM-REF/30529/2017 (NanoCell2SEC) and European Topology Interdisciplinary Action (EUTOPIA CA17139). A. F. M. Santos also acknowledges FCT-MCTES for the PhD Grant (SFRH/BD/132551/2017).
References:
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[4] A. F. M. Santos, C. Santos, M. H. Godinho, M. Dionísio, J. L. Figueirinhas, L. C. Branco, Liquid Crystals, 2022, in press.