Ion-beam-induced crosslinking of polystyrene — still an unsolved puzzle

Abstract

Polystyrene (PS) is a polymer which predominantly undergoes crosslinking when bombarded with high energy particles. The number of intermolecular crosslinks G x formed per 100 eV deposited energy is determined by irradiating thin PS films with 0.3 MeV 1H, 1.5 MeV 18O, and 0.4 and 6.5 MeV 40Ar ions at room temperature in vacuo. The chosen ions cover a wide range of nuclear ( S n) and electronic ( S e) energy loss. From the results in combination with literature data it is inferred that the momentum transferring collisions via S n are about 20 times more effective in forming crosslinks than electronic excitations and/or ionizations. No simple relation seems to exist between G x and a linear combination of S n and S e.