Bio-inspired approaches towards molecular super-reflectors
Contact: Dr. Nathalie Katsonis, Associate Professor, n.h.katsonis@utwente.nl
http://www.utwente.nl/tnw/bnt/, University of Twente, The Netherlands
Keywords. Bio-inspired materials, chirality, light-responsive molecular switches, nanoparticles, liquid
crystals.
Our aim is to develop smart materials that are inspired by the multiscale,
sophisticated and stimuli-responsive architectures that are found in
nature. To this end, we rely on controlling the expression, transmission
and amplification of chirality, from the nanoscale (the molecule) to the
supramolecular level. This research implies a special focus on lightresponsive systems [1].
For this project we aim to mimic the unusual optical properties that
characterize the iridescent cuticle of scarab beetles (Fig. 1). In particular, Figure 1. Plusiotis gloriosa (A) A
we want to design and synthesize molecular materials with a broad and bright green color is seen in
intense reflection band, in the visible and/or in the infrared region. They unpolarized light or with a left
could be used as thin films on smart windows, to control transmission circular polarizer. (B) The green
color is mostly lost when seen
and reflection of solar light and energy in buildings. The main strategy through a circular polarizer.
we will employ (Fig. 2) is based on creating new helix-based
architectures by irradiation of liquid crystals doped with light-responsive molecular motors [2] or
switches [3].
Two approaches will be used primarily : 1)
Forming a polymer network once the helical
structure is modified by irradiation, thereby
locking the molecules in close proximity to the
polymer fibrils at specific orientations, and
harness the optical properties of the resulting gels.
2) Embedding nano-objects into photo-responsive,
chiral liquid crystals [4]. The defects that will be
formed locally are expected to enhance the optical
properties of the films, and the special optical
properties of metallic nano-objects will be
Figure 2. Schematic representation of a cholesteric liquid
harnessed also.
crystal, and of a photo-responsive molecular switch that can
be used to photo-control the structure of the cholesteric
helix.
[1] S. Iamsaard, S.J. Aßhoff, B. Matt, T. Kudernac, J.J.L.M. Cornelissen, S.P. Fletcher, N. Katsonis, Nature Chemistry 2014, 6,
229-235.
[2] T. Kudernac, N. Ruangsupapichat, M. Parschau, .B. Macia, N. Katsonis, S.R. Harutyunyan, K.H. Ernst, B.L. Feringa Nature
2011, 479, 208-211.
[3] N. Katsonis, E. Lacaze, A. Ferrarini, J. Mater. Chem. 2012, 22, 7088 - 7097.
[4] B. D. Matt, K. Pondmann, S. J. Asshoff, B. ten Haken, B. Fleury, N. Katsonis, 2014, submitted.