The electrified contact (CE) was mankind’s first and only source of electricity until the 18th century, but its true nature remains a mystery. Today, it is considered a critical component of technologies such as laser printers, LCD production processes, electrostatic coatings, separating plastics for recycling, etc., as well as being a major industrial hazard (electronic system failure, explosions in coal mines, fires in factories. chemical) Electrostatic discharge (ESD) with CEITRO ) the reason. A study published in 2008 character In a vacuum, I found that the ESD of simple duct tape was so strong that it produced enough X-rays to take X-ray pictures of a finger.

For a long time, two contact/shear materials were believed to be charged in opposite and uniform directions. However, after CE, two different surfaces are found to carry (+) and (-) charges. The formation of the so-called charge mosaic results in the experience of inherent heterogeneity of the materials in contact or the general “random nature” of CE.

A research team led by Professor Bartosz A. Grzybowski (Department of Chemistry) at the Center for Soft and Living Materials at the Institute for Basic Sciences (IBS) Ulsan National Institute of Science and Technology (UNIST) He has been investigating the source of the mosaic exports for more than a decade. The study, which is expected to help control the discharge of potentially dangerous static electricity, was recently published in the journal

Figure 1. Charge mosaics on contact-charged dielectrics. (a) In a conventional view, two electrically neutral materials (grey) are brought into contact and then separated charge uniformly (lower left), one positive (red) and one negative (blue). In an alternative scenario (lower right), each surface develops a highly non-uniform ‘charge mosaic’ with neighboring domains of opposite charge polarities. (b) Collage of charge mosaics reported in the literature (the years and scale bars are indicated). Credit: UNIST

In the paper published recently in Nature Physics, the group of Professor Grzybowski shows that charge mosaics are a direct consequence of ESD. The experiments demonstrate that between delaminating materials the sequences of “sparks” are created and they are responsible for forming the (+/-) charge distributions that are symmetrical on both materials.

“You might think that a discharge can only bring charges to zero, but it actually can locally invert them. It is connected with the fact that it is much easier to ignite the ‘spark’ than to extinguish it,” says Dr. Yaroslav Sobolev, the lead author of the paper. “Even when the charges are reduced to zero, the spark keeps going powered by the field of adjacent regions untouched by this spark.”

The proposed theory explains why charge mosaics were seen on many different materials, including sheets of paper, rubbing balloons, steel balls rolling on Teflon surfaces, or polymers detached from the same or other polymers. It also hints at the origin of the crackling noise when you peel off a sticky tape – it might be a manifestation of the plasma discharges plucking the tape like a guitar string. Presented research should help control the potentially harmful electrostatic discharges and bring us closer to a true understanding of the nature of contact electrification, noted the research team.

References: “Charge mosaics on contact-electrified dielectrics result from polarity-inverting discharges” by Yaroslav I. Sobolev, Witold Adamkiewicz, Marta Siek and Bartosz A. Grzybowski, 8 September 2022, Nature Physics.
DOI: 10.1038/s41567-022-01714-9

“Correlation between nanosecond X-ray flashes and stick-slip friction in peeling tape” by Carlos G. Camara, Juan V. Escobar, Jonathan R. Hird and Seth J. Putterman, 23 October 2008, Nature. 
DOI: 10.1038/nature07378

“The mosaic of surface charge in contact electrification” by H. T. Baytekin, A. Z. Patashinski, M. Branicki, B. Baytekin, S. Soh and B. A. Grzybowski, 23 June 2011, Science.
DOI: 10.1126/science.1201512