Appearance modification by nano-patterning - GDR APPAMAT

Abstract

Living organisms have developed many strategies to produce colors and to modify appearance. Even if the use of pigments is widely spread, the effects produced by micro/nano patterning allow a larger range of possibilities. Indeed, the structuration of materials on multiple levels combined with intrinsic material properties offer a wide range of visual effects such as: metallic effect (possible without metal layer), gonio-chromatic appearance, glossy or mat surfaces (which can lead to efficient contrast effects), or super water repealing surfaces (which can punctually and locally change the surface appearance). In this way, surface patterning can generate aesthetic mimicking the beetles which often show gold or metallic green chitin shell due to 3D photonic crystal structures. However, they can also lead to wider optical effects to mimic moth eyes, which are super effective at capturing light at night thanks to nano-cones preventing the reflection of light.
These effects are very attractive since they rely only on physical and topographical properties, bringing possibilities to create colors and optical effects without chemical modification or add-on. While, the patterning process is a bottom up approach for living creatures, it can easily be replicated using top down microelectronics production technologies. However, a key challenge is the scale of the patterning areas (from cm² up to m²) and flat surfaces.
We report here the use of such micro-nano patterns in order to change the visual aspect of common material over large surfaces. SILSEF and NAPA have developed together a range of processes to functionalize surfaces for hydrophobicity, diffraction or antireflection. These technologies can be used on areas from mm² to m² on flat and hemispheric surfaces. Combined with effective characterization process developed internally, we aim to bring micro nano patterning to a range of industrial applications from fashion textile to windows glass. We show here functional patterning for decoration using diffractive or diffusive optics or water repellent surfaces as depicted on Figure 1.

Full text

Valentin Gâté1,2 , Colette Turbil 1,2, Simon Kolb2, Daniel Turover 1,2
1SILSEF, 382 rue Louis Rustin –Archamps Technopole, F-74160 Archamps
2NAPA Technologies, 382 rue Louis Rustin –Archamps Technopole, F-74160 Archamps
Attractive effects inspired by the nature…
Anti reflection effect of moth eyes
Change of effective surface refractive index
thanks to high aspect ratio of the pattern
Iridescence and coloration effects
Induced by the
periodic arangment of photonics crystals
Local change of appearance by water repellency
Double scale structuration (micro and nano
Superhydrophobicity in perfection: the outstanding
properties of the lotus leaf, Hans J Ensikat,et al.
We propose fast and cost-effective processes to engineer the
appearance of various materials by nano and micro scale patterning.
Such processes are applicable to surfaces up to m² dimensions, so they
can lead to the large-scale / volume production or either to realize model
surfaces for fundamental studies.
We would like to acknowledge the financial
support of ANR (projects “SINCRONE”,
“SPOT”, ASTRID “OPERA”)
and DGA (“BISONS”)
Conclusion & perspective Acknowledgements
Appearance modification by nano-patterning
… are mimicked in the laboratory …
3 - Reproduction
Etching
Embossing
Injection
moulding
µ-contact
printing
2 - Tools fabrication
Fabrication of micro-nano
patterned tools: masks,
stamps, injection molds,…
4 - Control
Topography: AFM, SEM
Optics: spectrophotometer
Wettability:
« ALPIN »
test bench
Fog/Frost:
« BCBG »
1 - Functional design
d
P’
h
Side view
Design from simulation or experience
Large catalogue of patterns available
d
P’
P’
d
P’
P’
Top view
…to manufacture functional products on various materials
Anti reflection and contrast
Diffusive pattern preventing
specular reflection
Local diffractive pattern leading to high
contrast effects (marking applications)
Coloration and decoration
Coloration and shining from diffractive gratings
Decorative patterns
on leather or fabrics
Hydrophobicity and anti-frost
Local double texturation to produce
superhydrophobic and anti-frost effects
T0T0 + 2’ T0 + 4’
Study of the contact angle between
different couple of liquids / materials
Nano-pattening on glass surfaces using
SiO2sol-gel process:
•Flat surfaces or lenses
•From cm² up to m² dimensions
•Single side or multiface objects
Functionnal textures can be transfered onto
leather,fabric, polymers and metals by:
•Hot embossing
•Injection molding
•Wet/dry etching
Options to use resin, varnish, or sol-gel
coatings to change:
•Optics (refractive index, color,…)
•Mechanics (abrasion, strain,…)
•Adhesion on substrate
Numerous possibilities to create innovative surfaces and products