Electric Glue Using Nanoscale Systems

Astonished? Do not be. The term electric glue means a sticky material made up from nanoscale systems in which the adhesion or the adhesive property is controlled electrochemically. How do glues adhere or stick to solid materials? It is due to the physical or the chemical interactions between the glue and the surface of the object on which the glue is applied. The time when this interaction actually starts or the objects start getting glued is determined by the “time required for the chemical reaction” or “rate of evaporation of the solvent”.



There are various forms of glues of which one is based on the property of electric adhesion. In this process the electrostatic fields do the job of attracting the dye particles to the surfaces of the objects. Hermann E. Gaub a professor of physics at the Ludwig-Maximilians-University (LMU) is of the opinion that we need to control the interaction of a polymer with an electrode surface reversibly which in turn creates a nanoscale system with electrochemically controlled adhesion if we want to make an electric glue.

This arises from the fact that Coulomb’s forces existing between the polymer molecules and the electrode surfaces can be measured, controlled and manipulated. This is done by an externally controlled potential applied between the glue and the surface.

And guess what? This glue is not a permanent one. It can be switched on and off as and when required depending on the geometry. Gaub says “For example, objects to be glued may be aligned carefully and only when optimum alignment is reached, the voltage is switched to hold." The bonding can be weakened when adhesion is not required. The tuning of this coefficient of adhesion is done by inserting a “backbone charge” to the polymer. The insertion is done in such a manner that the end group of the polymer reacts with the electrode or does not depending upon the potential applied. An “Atomic force microscope” was used to explore this phenomenon in which gold working electrode was the object of interest.

A series of experiments were carried out involving three polymers with different backbone charges and primary amine acting as an end group. This phenomenon was successful not only with the biopolymers, but also with the synthetic polymers. The bonding between the polymer and electrode was governed by two factors:
<ul>
[*]Influence of backbone charges
[*]Oxidation state of the gold electrode
</ul>
This concept is being studied and developed further but the prominent milestones to overcome in the process are:
<ul>
[*]Increasing polymer density
[*]Bridging the polymers between the two surfaces to be glued
[*]Amelioration of the holding forces
[*]Increasing hysterisis between the high and the low forces
</ul>
Source: NanoWerk Posted in: #Coffee Room