Mimicking the Nature to Achieve Superhydrophobic Surfaces by Vapor Phase Deposition
- PDF / 1,839,890 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 110 Downloads / 171 Views
1008-T08-25
Mimicking the Nature to Achieve Superhydrophobic Surfaces by Vapor Phase Deposition Sushant Gupta1, Arul Arjunan Chakkaravarthi1, Rajiv Singh1, Nate Stevens2, Jeff Opalko3, and Deepika Singh3 1 Materials Science & Engineering, University of Florida, 100 Rhines Hall, Gainesville, FL, 32611 2 Particle Engineering Research Center, University of Florida, P.O. Box 116135, Gainesville, FL, 32611 3 Sinmat Inc., 2153 Hawthorne Road, Suite 129 (Box 2), Gainesville, FL, 32641 ABSTRACT A novel technique was developed to create superhydrophobic polytetrafluoroethylene (PTFE) surface using nanosecond pulse electron deposition (PED) technique. The PTFE or Teflon thin films deposited on silicon substrate showed superhydrophobicity evidenced by the contact angle of 166±2°. The SEM micrographs reveal the clustered growth of the deposited film and two level sub-micron asperities which is corroborated by the AFM. FTIR and contact angle studies were conducted to study the chemical nature and the wetting properties of the films. INTRODUCTION The surface chemistry and surface topography affect the surface interactions of the material with liquids. There are two basic approaches to minimize these interactions. One of the approaches is to change the surface chemistry i.e. lower the surface energy (the chemical method) and the other is to increase the surface roughness (the geometrical method). It is well known that the superhydrophobicity is observed in nature (e.g. Lotus leaf) which is attributed to the hierarchical roughness (from micrometer to nanometer scale) of the leaf surface. Many efforts have been made to replicate such asperities. Various methods adopted for their synthesis usually involves two steps: (a) deposition of films and (b) controlling the surface roughness by techniques such as plasma treatment [1], etching or deposition/surface functionalization of patterned surfaces [2, 3]. Here we present a novel single step technique to synthesize superhydrophobic surfaces using pulse electron deposition. Owing to PTFEís low surface energy it shows hydrophobicity with a water contact angle of ~109∞. Further, low adhesion, low permeability and high chemical stability makes PTFE an excellent choice as starting material for preparation of superhydrophobic surfaces [4, 5]. The surface roughness of PTFE thin films was controlled by varying the deposition parameters to achieve the superhydrophobicity. EXPERIMENTAL Nanosecond (100 ns) pulse electron gun, PEBS-20 model from Neocera Inc. was used for deposition of PTFE thin films on silicon (p-type) substrates. A schematic of the PED system is shown in figure 1. Circular disc of 1î diameter was cut from a Teflon sheet (Fisher Scientific) to form the target. The target disc was sonicated in acetone for 5 min and dried subsequently. The films were deposited at various pulse energies (between 5-20 keV) at the repetition rate of 5Hz and the number of pulses for each run was kept constant at 104. Prior to deposition the chamber
was evacuated to 10-5 torr and during deposition the c
Data Loading...
