Loading the DICE: Dynamics of Ion Contact Electrification

Contact electrification, while sounding complicated, is actually a very simple phenomena to understand. We all can picture what happens when we rub a balloon on our hair. If our hair is long enough, it will often stand on end. The reason this occurs is due to the transfer of charges from one material to another (between our hair and the balloon). Our hair becomes charged, all in the same sign, which means that our hairs want to repel from each other, with the final result being a messed-up hairdo. While the process of charge transfer occurring during contact (contact electrification) may seem simple, it actually isnt fully understood. People have postulated what the mechanism of charge transfer is for the past 2600 years and no clear understanding of the entire process has been proven to date. During that time a few breakthroughs have been uncovered, specifically what might be the charge carrier. These are either electrons (negatively charged subatomic particles), ions (atoms which have an unequal balance of protons and electrons, thus exhibiting a net charge), or very small pieces of material which might transfer from one surface to another, resulting in some charging affect. Also, it has been experimentally proven that charge transfer between two metals occurs due to electron transfer. The jury is still out on what occurs between non-conducting materials. The aims of this research project are to the help shed light on the charge transfer process, by specifically examining how ion transfer occurs during contact electrification. This will be achieved by tailoring our material choice to that of ionomers. These materials contain a surface of fixed charge groups, which are associated with a separate, mobile ion group. This mobile ion group is able to transfer between surfaces during contact, which results in a measurable charge transfer. This process has been demonstrated previously in the field of contact electrification and we aim to expand on this by systematically evaluating 1) how the specific interactions between the fixed and mobile ions influence charge transfer, 2) how fundamentally ions traverse from one surface to another, and 3) if it is possible to control the extent of charge transfer through patterned surface domains. We hope to further the field of contact electrification through this work of examining one of the three possible charge carriers in contact electrification. While not answering all the question of contact electrification, this approach allows us to fully understand what leads to ion transfer during contact, which in turn creates a more complete picture of the phenomena.