Fabrication of micro‐ and nanostructures at line‐speed of 60 m min−1 by large‐area roll‐to‐roll extrusion coating is demonstrated. Nanopillars with diameters 80 nm and heights 100 nm are replicated in polypropylene. The main limiting factor for replication on nanoscale is the retardation time for solidification of the melt.
Lab-scale plasmonic color printing using nano-structured and subsequently metallized surfaces have been demonstrated to provide vivid colors. However, upscaling these structures for large area manufacturing is extremely challenging due to the requirement of nanometer precision of metal thickness. In this study, we have investigated a plasmonic color meta-surface design that can be easily upscaled. We have demonstrated the feasibility of fabrication of these plasmonic color surfaces by a high-speed roll-to-roll method, comprising roll-to-roll extrusion coating at 10 m min creating a polymer foil having 100 nm deep pits of varying sub-wavelength diameter and pitch length. Subsequently this polymer foil was metallized and coated also by high-speed roll-to-roll methods. The perceived colors have high tolerance towards the thickness of the metal layer, when this thickness exceeds the depths of the pits, which enables the robust high-speed fabrication. This finding can pave the way for plasmonic meta-surfaces to be implemented in a broader range of applications such as printing, memory, surface enhanced Raman scattering (SERS), biosensors, flexible displays, photovoltaics, security, and product branding.
We demonstrate the
use of roll-to-roll extrusion coating (R2R-EC)
for fabrication of nanopatterned polypropylene (PP) foils with strong
antiwetting properties. The antiwetting nanopattern is originated
from textured surfaces fabricated on silicon wafers by a single-step
method of reactive ion etching with different processing gas flow
rates. We provide a systematic study of the wetting properties for
the fabricated surfaces and show that a controlled texture stretching
effect in the R2R-EC process is instrumental to yield the superhydrophobic
surfaces with water contact angles approaching 160° and droplet
roll-off angles below 10°.
a b s t r a c tSurface roughness or texture is the most visible property of any object, including injection molded plastic parts. Roughness of the injection molding (IM) tool cavity directly affects not only appearance and perception of quality, but often also the function of all manufactured plastic parts. So called "optically smooth" plastic surfaces is one example, where low roughness of a tool cavity is desirable. Such tool surfaces can be very expensive to fabricate using conventional means, such as abrasive diamond polishing or diamond turning. We present a novel process to coat machined metal parts with hydrogen silsesquioxane (HSQ) to reduce their surface roughness. Results from the testing of surfaces made from two starting roughnesses are presented; one polished with grit 2500 sandpaper, another with grit 11.000 diamond polishing paste. We characterize the two surfaces with AFM, SEM and optical profilometry before and after coating. We show that the HSQ coating is able to reduce peak-to-valley roughness more than 20 times on the sandpaper polished sample, from 2.44(±0.99) m to 104(±22) nm and more than 10 times for the paste polished sample from 1.85(±0.63) m to 162(±28) nm while roughness averages are reduced 10 and 3 times respectively. We completed more than 10,000 injection molding cycles without detectable degradation of the HSQ coating. This result opens new possibilities for molding of affordable plastic parts with perfect surface finish.
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