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

A series of sterically-stabilized polystyrene latex particles in the size r ange 0.1-5.0 mu m have been coated with ultrathin (<50 nm) overlayers of ei ther 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 adv antages compared to the sterically-stabilize polypyrrole particles of 0.1-0 .3 mu m diameter reported previously. First, a wider particle size range ca n be accessed. Second, the particle size distributions of the coated latexe s are much narrower than those of the pure polypyrrole particles reported e arlier. Preliminary studies confirm that, after charging and acceleration, these co nducting polymer-coated latex particles have very similar mass-velocity pro files to those reported for colloidal iron particles in the hypervelocity l iterature. The hypervelocity impact generated ionization has been measured for latex spheres impacting copper targets. This is compared to previous wo rk for impact ionization by iron particles, thus demonstrating the ability to study the dependence of impact ionization on widely different projectile materials.