Difference between revisions of "Controlling the Kinetics of 'Contact Electrification' with Patterned Surfaces"

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[[Image:Electric 1.jpg]]
 
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== Title 1==
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== Suppression of Net Charge==

Revision as of 17:47, 4 November 2011

Original entry by Andrew Capulli, AP225 Fall 2011

Reference

"Controlling the Kinetics of Contact Electrification with Patterned Surfaces", Thomas, S.W., Vella, S.J., Dickey, M.D., Kaufman, G.K., and Whitesides, G.M., Journal of American Chemical Society, 2009, 131, 8746-8747

Introduction: Motivation

All it takes is a single spark... There are numerous examples of tragedy from the discharge of contact charged (tribocharged) surfaces. Be it the explosion of fuel transfer systems or helicopters landing, these sometimes 'playful' static charges we're all familiar with by rubbing our feet on carpet and shocking each other, can turn into costly and very deadly 'shock' discharges. NASA follows a strict "triboelectrification rule" which grounds any mission if the clouds a shuttle is predicted to fly through may result in a potentially unsafe surface charge on the vehicle (see triboelectric effect: http://en.wikipedia.org/wiki/Triboelectric_effect). There must then be a means of controlling the triboelectric effect... minimize its effect on contacting materials so as to reduce charge build up which would then reduce the deadly discharge. This is the goal of the authors as they provide a means of surface modification based on the ion-transfer mechanism. The ion-transfer mechanism can be briefly summarized in Figure 1 below. Figure 1 is taken from another paper by Professor Whitesides entitled: "Ionic Electrets: Electrostatic Charging of Surfaces by Transferring Mobile Ions upon Contact" and can be found at: http://gmwgroup.harvard.edu/pubs/pdf/988.pdf. Essentially, a surface with covalently bound ions is neutralized by the 'mobile counterion'. If another surface comes in contact with the given surface, the mobile counterion is 'transferred' to this other surface and consequently a net charge is left on each surface (see Figure 1 below):

Electric 1.jpg

Suppression of Net Charge