scholarly journals Direct generation of superhydrophobic microstructures in metals by UV laser sources in the nanosecond regime

2016 ◽  
Vol 5 (1) ◽  
Author(s):  
Jose L. Ocaña ◽  
R. Jagdheesh ◽  
J.J. García-Ballesteros
Keyword(s):  
Contact Angle ◽  
Laser Pulses ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Contact Friction ◽  
Structured Surfaces ◽  
Wetting Properties ◽  
Aluminum Sheets ◽  
Static Contact ◽  
Laser Sources

AbstractThe current availability of new advanced fiber and DPSS lasers with characteristic pulse lengths ranging from ns to fs has provided a unique frame in which the development of laser-generated microstructures has been made possible for very diverse kinds of materials and applications. At the same time, the development of the appropriate laser-processing workstations granting the appropriate precision and repeatability of the respective laser interaction processes in line with the characteristic dimension features required in the microstructured samples has definitively consolidated laser surface microstructuring as a reference domain, nowadays, unavoidable for the design and manufacturing of current use microsystem: MEMSs, fluidic devices, advanced sensors, biomedical devices and instruments, etc., are all among the most well-known developments of the micromanufacturing technology. Completing the broad spectrum of applications developed mostly involving the generation of geometrical features on a subtrate with specific functional purposes, a relatively new, emerging class of laser-microstructuring techniques is finding an important niche of application in the generation of physically structured surfaces (particularly of metallic materials) with specific contact, friction, and wear functionalities, for whose generation the concourse of different types of laser sources is being found as an appropriate tool. In this paper, the application of laser sources with emission in the UV and at ns time regime to the surface structuration of metal surfaces (specifically Al) for the modification of their wettability properties is described as an attractive application basis for the generation of self-cleaning properties of extended functional surfaces. Flat aluminum sheets of thickness 100 μm were laser machined with ultraviolet laser pulses of 30 ns with different laser parameters to optimize the process parameters. The samples produced at the optimum conditions with respect to contact angle measurement were subjected to microstructure and chemical analysis. The wetting properties were evaluated by static contact angle measurements on the laser-patterned surface. The laser-patterned microstructures exhibited superhydrophobicity with a maximum contact angle of 180° for the droplet volumes in the range of 8–12 μl.

Preparation and the Blood Compatibility of Titanium Oxide Nanorod Arrays

2011 ◽  
Vol 306-307 ◽  
pp. 25-30 ◽  
Author(s):  
Ping Luo ◽  
Zhan Yun Huang ◽  
Di Hu Chen
Keyword(s):  
Contact Angle ◽  
Surface Morphology ◽  
Titanium Oxide ◽  
Tin Oxide ◽  
Growth Parameters ◽  
Blood Compatibility ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Nanorod Arrays ◽  
Wetting Properties

In this work, titanium oxide nanorod arrays were fabricated by using the hydrothermal method on fluorine-doped tin oxide (FTO) coated glass. The diameter of the nanorods could be controlled from 150 nm to 30 nm by changing the growth parameters. The surface morphology and the structure of the samples were characterized by SEM and XRD. The wetting properties were identified by contact angle measurement. Platelet attachment was investigated to evaluate the blood compatibility of the samples with different nanoscale topographies. Results show that the nanotopographical surfaces perform outstanding blood compatibility, and the adhering platelet decreased with the increasing diameter of the nanorods.

Contact Angle Measurement in the Environmental Scanning Electron Microscope (ESEM)

2000 ◽  
Vol 6 (S2) ◽  
pp. 780-781
Author(s):  
J.P. Craven ◽  
N.A. Stelmashenko ◽  
E.M. Terentjev ◽  
B. L. Thiel
Keyword(s):  
Contact Angle ◽  
Water Vapour ◽  
High Pressures ◽  
Water Pressure ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Petroleum Engineering ◽  
Optical Methods ◽  
Depth Of Field ◽  
Wetting Properties

The ESEM uses a novel differential pumping system combined with a pressure-limiting aperture to achieve relatively high pressures of up to 10 torr in the specimen chamber. Using this system allows samples to be imaged in the presence of water vapour or other gases. Conveniently the saturated water pressure at 275K lies within this range, allowing the stabilisation of hydrated samples, condensation from water vapour and evaporation to be performed in situ within the microscope chamber.Wetting of surfaces is of fundamental importance in many different areas of science, from textiles to petroleum engineering. The ESEM now provides an opening for high-resolution studies of these phenomena without the problematic depth-of-field limitations that optical methods present. The contact angle, θ, is defined as the angle between the tangent to the liquid-fluid interface and the tangent to the solid interface. It provides a ready indication to the wetting properties of a system.

scholarly journals Preparation of Superhydrophobic Teflon® AF 1600 Sub-Micron Fibers and Yarns Using the Forcespinningtm Technique

2013 ◽  
Vol 8 (4) ◽  
pp. 155892501300800 ◽  
Author(s):  
Yatinkumar Rane ◽  
Aleksey Altecor ◽  
Nelson S. Bell ◽  
Karen Lozano
Keyword(s):  
Surface Roughness ◽  
Contact Angle ◽  
Average Diameter ◽  
Contact Angle Measurement ◽  
Contact Angles ◽  
Angle Measurement ◽  
Sem Analysis ◽  
Fiber Formation ◽  
Excellent Thermal Stability ◽  
Wetting Properties

Superhydrophobic materials combined with manufacturing processes that can increase surface roughness of the material, offer an opportunity to effectively control wetting properties. Rapid formation of Teflon® AF (TAF) fibrous mats with sub-micron fiber diameter using the Forcespinning™ technique is presented. The fiber formation technique is based on the use of centrifugal forces. SEM analysis shows uniform formation of TAF 1600 fibers with average diameter of 362±58nm. Contact angle measurement confirms the superhydrophobic nature of the mats with contact angles as high as 169° ± 3° and rolling angles of 2°. TAF 1600 mats were forcespun at a rate of 1gr/min. The relationship between the contact angle and hierarchical surface roughness of the TAF mat is also discussed. TAF yarns were also manufactured and characterized. Yarns with diameters of 156 microns withstood 17.5 MPa of engineering stress with a Young's modulus of 348 MPa in the elastic region and excellent thermal stability.

scholarly journals Structural and wetting properties of nature's finest silks (order Embioptera)

2018 ◽  
Vol 5 (9) ◽  
pp. 180893 ◽  
Author(s):  
Grace Y. Stokes ◽  
Evangelea N. DiCicco ◽  
Trevor J. Moore ◽  
Vivian C. Cheng ◽  
Kira Y. Wheeler ◽  
...  
Keyword(s):  
Contact Angle ◽  
Related Species ◽  
Fibre Diameter ◽  
Contact Angle Measurement ◽  
Contact Angles ◽  
Angle Measurement ◽  
Adhesive Properties ◽  
Adhesion Properties ◽  
Static Contact ◽  
Water Adhesion

Insects from the order Embioptera (webspinners) spin silk fibres which are less than 200 nm in diameter. In this work, we characterized and compared the diameters of single silk fibres from nine species— Antipaluria urichi , Pararhagadochir trinitatis , Saussurembia calypso , Diradius vandykei , Aposthonia ceylonica , Haploembia solieri , H. tarsalis , Oligotoma nigra and O. saundersii . Silk from seven of these species have not been previously quantified. Our studies cover five of the 10 named taxonomic families and represent about one third of the known taxonomic family-level diversity in the order Embioptera. Naturally spun silk varied in diameter from 43.6 ± 1.7 nm for D. vandykei to 122.4 ± 3.2 nm for An. urichi. Mean fibre diameter did not correlate with adult female body length. Fibre diameter is more similar in closely related species than in more distantly related species. Field observations indicated that silk appears shiny and smooth when exposed to rainwater. We therefore measured contact angles to learn more about interactions between silk and water. Higher contact angles were measured for silks with wider fibre diameter and higher quantity of hydrophobic amino acids. High static contact angles (ranging up to 122° ± 3° for An. urichi ) indicated that silken sheets spun by four arboreal, webspinner species were hydrophobic. A second contact angle measurement made on a previously wetted patch of silk resulted in a lower contact angle (average difference was greater than 27°) for all four species. Our studies suggest that silk fibres which had been previously exposed to water exhibited irreversible changes in hydrophobicity and water adhesion properties. Our results are in alignment with the ‘super-pinning’ site hypothesis by Yarger and co-workers to describe the hydrophobic, yet water adhesive, properties exhibited by webspinner silk fibres. The physical and chemical insights gained here may inform the synthesis and development of smaller diameter silk fibres with unique water adhesion properties.

Elemental Analysis and Wettability Properties of Polyene with Epoxidised Oil Based Coating

2013 ◽  
Vol 701 ◽  
pp. 389-393
Author(s):  
Mohd Nurazzi Norizan ◽  
Rahmah Mohamed
Keyword(s):  
Contact Angle ◽  
Reaction Time ◽  
Structural Feature ◽  
Elemental Analysis ◽  
Degradation Process ◽  
Contact Angle Measurement ◽  
Angle Measurement ◽  
Chlorine Content ◽  
X Ray ◽  
Static Contact

Presence of chlorine in by product of degradation process from polyvinyl chloride was analysed through structural feature changes and elemental analysis. Coating samples with polyene was also tested for its wettability via contact angle. Analyzing the elimination of chlorine content from polyvinylchloride through chemical dechlorination with tetrahydrofuran (THF) has been studied via FTIR spectra, energy-dispersive x-ray spectroscopy (EDS) and static contact angle measurement. Qualitative value of decreasing chlorine content of polyene at 2 hours reaction time was found to be about 96% from supplied PVC. All treated samples at different reaction time of polyene synthesize showed good wettability properties since the contact angle value were less than 90o.

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