  Triboelectric charging strongly affects the operation cycle and handling of
materials and can be used to harvest mechanical energy through triboelectric
nanogenerator set-up. Despite ubiquity of triboelectric effects, a lot of
mechanisms surrounding the relevant phenomena remain to be understood.
Continued progress will rely on the development of rapid and reliable methods
to probe accumulation and dynamics of static charges. Here, we demonstrate
in-situ quantification of tribological charging with nanoscale resolution, that
is applicable to a wide range of dielectric systems. We apply this method to
differentiate between strongly and weakly charging compositions of industrial
grade polymers. The method highlights the complex phenomena of electrostatic
discharge upon contact formation to pre-charged surfaces, and directly reveals
the mobility of electrostatic charge on the surface. Systematic
characterization of commercial polyethylene terephthalate samples revealed the
compositions with the best antistatic properties and provided an estimate of
characteristic charge density up to 5x10-5 C/m2. Large-scale molecular dynamics
simulations were used to resolve atomistic level structural and dynamical
details revealing enrichment of oxygen containing groups near the air-interface
where electrostatic charges are likely to accumulate.
