Maria Helena Godinho
ai3N/CENIMAT, Department of Materials Science, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Campus de Caparica, 2829-516, Caparica, Portugal.

“Travelling colourful patterns in cellulose-based liquid crystalline systems”

Imprinted by plants cellulose chiral molecules generate left (L)-handed, right (R) – handed and achiral structures, at different length scales. This behavior, although poorly understood, is ubiquitous not only in plants but also in self-assembled materials prepared by man, as in cellulosic liquid crystalline systems. In this seminar the inversion of the helix handedness is illustrated by the use of a cellulose-based lyotropic system. The lyotropic solutions, confined in 1D and 2D geometries, show a sequence of periodic patterns, allowing in a single preparation to observe simultaneously the L and R structures. The experimental results evidence that the inversion of the helix handedness is driven by the self-adjustment of the conformation of the cellulosic chain to the environment. The evolution of the system is generated by a reaction diffusion mechanism and the evaporation of solvents at the boundaries. Foreseen technological applications include the manipulation of structural colours, the preparation of templates and the design of hydrophilic/hydrophobic surfaces on demand.

Pedro E. S. Silva, Ricardo Chagas, Susete N. Fernandes, Pawel Pieranski, Robin L. B. Selinger, and Maria Helena Godinho, Communications Materials, 2021 (accepted).

This work is co-financed by FEDER, European funds, through the COMPETE 2020 POCI and PORL, National Funds through FCT – Portuguese Foundation for Science and Technology and POR Lisboa2020, under the projects PIDDAC (POCI-01-0145-FEDER-007688, Reference UIDB/50025/2020-2023) and PTDC/CTM-REF/30529/2017 (NanoCell2SEC) and Action European Topology Interdisciplinary Action (EUTOPIA CA17139).