Layer-by-Layer
Electrostatic Self-Assembly

The ND dip coaters are intended for the fabrication and deposition of thin films on different surfaces by dip coating. The ND coaters are the ideal equipment for the fabrication of different types of homogeneous films: sol-gel, polymeric layers, multilayer structures, biofilms, antibodies or enzymes deposition, etc. The range of application is very extensive, including the fabrication of solar cells, electronic components, sensors, anti-reflection films, smart coatings, protective films or biocides films.

ND-DC
Dip Coater

The vertical moving system of the ND-DC Dip Coater allows the fabrication of diverse types of homogeneous films. The immersion and dipping-out speed rates range from a minimum of 10 microns per minute to a maximum speed of 150 millimeters per minute. This broad range of programmable dipping rates combined with such high precision enables the fabrication of very thin films by wet deposition, sol-gel processing or self-assembled monolayers.

ND-R Rotary
Dip Coater

The ND-R Rotary Dip Coater enjoys a 2-axis programmable system. One axis is for vertical displacement and the other for the rotation in the horizontal plane. This configuration offers a high versatility for multistep deposition which requires the consecutive immersion in vessels with different solutions. Depending of the volume and size of the vessels used for the deposition, from 4-steps cycles (using 4 standard 250 ml beakers) to 8-steps cycles (using 8 standard 50 ml beakers) can be arranged with the standard ND-R Coater. In addition, it is possible to request an optional deposition module for the simultaneous dipping of 4 different substrates.

ND Layer-by-Layer
Dip Coater

The Nadetech ND-2D & ND-3D Multi Axis Dip Coaters are a system developed for the fabrication of thin films by wet deposition. The Multi Axis system enjoys a 2 or 3 axis programmable cartesian system. This configuration offers a high versatility for multistep deposition which requires the consecutive immersion in vessels with different solutions. Its wide range allows depositing multiple samples at the same time. Moreover, its wide dipping out rates, which allows working from a minimun rate of 0.6 mm per inute to a maximum rate of 1000 mm per minute.

Technology

Dip Coating

Dip Coating is a widely used deposition technique used to obtain nanometric films. Dip Coating deposition process can be divided into five steps. In the continuous process, the steps are carried out directly after each other:

  • Immersion: The substrate is immersed into a solution of the material to be deposited at a constant immersion rate.
  • Starting: The substrate which has been dipped into the solution for a determinate period of time starts to be pulled up.
  • Deposition: The film is deposited on the substrate while is pulled up. The withdrawal is carried out at a constant rate, avoiding any undesired vibration. The withdrawal speed determines the thickness of the deposited film (a higher speed produces a thicker film).
  • Drainage: The excess of liquid is drained from the surface.
  • Evaporation: The solvent is evaporated from the deposited liquid film, resulting on the coating. For volatile solvents, such as alcohols, the evaporation process starts during the deposition and drainage steps.
The precise control of the immersion speed, the immersion time and the withdrawal speed influences the depth and the characteristics of the resultant coating. This process is carried out with the help of a ND-DC Dip Coater, ND-R Rotary Dip Coater or a ND-Multi Axis Dip Coater in which all these parameters can be easily controlled. After the deposition, a drying time is needed or an ageing heat treatment can be applied, in order to reduce the humidity of the film and guarantee its stability.

Layer-by-Layer

ELECTROSTATIC SELF-ASSEMBLY
El método de Autoensamblado Electrostático (ESA) permite la formación de manera uniforme de múltiples capas de espesor nanométrico.

The Layer-by-Layer (LbL) assembly also called Electrostatic Self Assembly Multilayer (ESAM), consists of the immersion of the substrate into alternate solutions with opposite electric charge [1]. This electrostatic attraction is the main force of adhesion to the surface of the substrate. It was discovered in 1966 although this technique went unnoticed until the nineties, when G. Decher and coworkers rediscovered the LbL technique [2]. Since then, the LbL assembly has become one of the most popular methods to obtain nanometric coatings.

The LbL assembly is a multistep process, in which the different electrostatic attraction forces of the polyelectrolyte solutions keep the coating together. The almost perfect order at the molecular level of the individual monolayers is the result of many individual molecules reaching their minimum energy configurations locally. They are adsorbed from the aqueous solutions and bind with molecules previously fixed to the substrate. The interpenetration of molecules in adjacent layers can be controlled to improve the macroscopic properties of the material.

LbL technique offers some important advantages in comparison with other coating techniques, as it is a simple technique, it can be used to coat complex geometries with homogeneous results and allows to control the thickness of the film. Many kinds of substances can be deposited by LbL technique, such as nanoparticles, polymers, fluorescent indicators and colometric compounds.

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