Earlier this year, I had learnt in Physics class that rubbing two different materials against each other can charge the materials (i.e. cause each material to either be positively-charged or negatively-charged). I had learnt that the charging process is an electron transfer phenomenon. The charging of conductors by rubbing (i.e. friction) is easily understood because conductors allow charge carriers to flow through them easily. Such as in the case of metals; adding more electrons to the sea of delocalised electrons is not difficult.

However, what happens during the charging of an insulator material, such as a polymer like poly(ethene), what happens to electrons which are transferred to these materials? Do they go into particular orbitals?

One thing I am sure of is that the electrons are surely localised to the region of the insulator they are transferred to. Thus, they are definitely not free moving.

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    $\begingroup$ This is a good question. However, I fear it may have to be closed as a duplicate of [chemistry.stackexchange.com/questions/76711/…. Your question is specifically about insulators, but the question I linked deals with triboelectricity in general (so your question could be a subset of that). If not this, then it is still a cross-site duplicate of this question [physics.stackexchange.com/questions/309653/…. Like I said; good question...but not sure if it'll remain open as it stands. O:) $\endgroup$ Jun 25 '17 at 10:08
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    $\begingroup$ @Paracetamol I guess you are right that it is a subset of the question on triboelectricity. However, it is different from the one on Physics SE because mine discusses chemistry of the interaction, not of energy and forces. $\endgroup$ Jun 25 '17 at 10:24
  • $\begingroup$ You're getting sure too easily (last sentences). This isn't "normal" chemistry. Presence of charge means there are very reactive cation/anion radicals all the time. $\endgroup$
    – Mithoron
    Jun 25 '17 at 17:55
  • $\begingroup$ @Mithoron Yes, I agree that there should be very reactive charged radicals and other reactive species in the insulator material. But we somehow cannot observe the reactions of these species. All we observe is that the negative charges present in the material repel negative charges in other materials. Also, regarding the part about localisation, I am indeed sure that the charges are localised. Because the teacher said that only the points of contact/rubbing were charged. He explained that the material lacked free charge carriers, since it is an insulator. $\endgroup$ Jun 26 '17 at 1:21

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