Acceleration of conducting polymer-coated latex particles as projectiles in hypervelocity impact experiments

Abstract

A series of sterically-stabilized polystyrene latex particles in the size range 0.1-5.0 µm have been coated with ultrathin (<50 nm) overlayers of either polypyrrole, polyaniline or poly(3,4-ethylenedioxythiophene). In each case the conducting polymer overlayer allows the latex particles to acquire surface charge and hence be accelerated up to hypervelocities (>1 km s-1) using a Van de Graaff accelerator. These coated latexes have two main advantages compared to the sterically-stabilized polypyrrole particles of 0.1-0.3 µm diameter reported previously. First, a wider particle size range can be accessed. Second, the particle size distributions of the coated latexes are much narrower than those of the pure polypyrrole particles reported earlier. Preliminary studies confirm that, after charging and acceleration, these conducting polymer-coated latex particles have very similar mass-velocity profiles to those reported for colloidal iron particles in the hypervelocity literature. The hypervelocity impact generated ionization has been measured for latex spheres impacting copper targets. This is compared to previous work for impact ionization by iron particles, thus demonstrating the ability to study the dependence of impact ionization on widely different projectile materials.