hierarchical photonic pigments via the confined self ... · the most brilliant coloursin nature are...
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Hierarchical photonic pigments via the confined self-assembly of bottlebrush block copolymers
Bio-Inspired Photonics
Richard Parker, Tianheng Zhao, Dong-Po Song, Silvia Vignolini
http://www.ch.cam.ac.uk/group/vignolini/
Colour and structure
Part of the light is absorbed, part is scattered (non-directional)
Part of the light is reflected (directional) part is transmitted.
Reflected colour is STRONG but the material is TRANSPARENT
The most brilliant colours in nature are obtained from wavelength-sized transparent structures.
Photonic structures in nature
S. Kinoshita, Structural Colors in the Realm of Nature (2008)O. Karthaus, Biomimetics in Photonics (2012)
Bottlebrush block copolymers (BBCPs)
P(PS-NB)(n = 1.59)
P(PDMS-NB)(n = 1.43)
Photonic films from BBCPs
100 μm
5 mm
BBCP2 BBCP3BBCP1
MW3.3 MDa 7.1 MDa
1.0 μm
P(PS-NB)(n = 1.59)
P(PDMS-NB)(n = 1.43)
P(PDMS-NB)(n = 1.43)
! = 2 $%& '
Photonic films from BBCPs
Hierarchical photonic pigments
iridescent non-iridescent
?
self-assembly + confinement à new functionality
Spherical confinement: microdroplets
0.0
0.2
0.4
0.6
0.8
1.0
400 500 600 700
Ref
lect
ance
Wavelength / nm
1+21+32+3
BBCP 2 BBCP 3
BBCP 13
12
1 + 2 (1:1)
1 + 3 (1:1)
2 + 3 (1:2)
25 μm
Expanding the colour palette
BBCP1 BBCP1 + CB
0.0
0.2
0.4
0.6
0.8
1.0
400 500 600 700N
orm
alis
ed re
flect
ance
Wavelength / nm
BBCP1
BBCP1 + CB
25 μm
Functional additive - enhance the contrast
ϴ = 5� 15� 30� 45�
diffuse illumination
direct illumination
ϴϴ
ϴ
ϴ = 5� 15� 30� 45�
2 wt% BBCP2
Structurally-coloured coatings
D.-P. Song, T.H. Zhao, G. Guidetti, S. Vignolini, R.M. Parker, ACS Nano, 2019, 13, 1764.
Hierarchical photonic pigments from BBCP microemulsions:• intense reflected colour – up to 100%• tuneable colour via the formulation• stimuli-responsive colour upon selective swelling
Robust interface-templated assembly process:• high tolerance to droplet size and drying rate• long-range order with minimal defects• functionality can be enhanced with additives
BBCP pigments can be embedded into coatings (e.g. paints)
Summary