Applying the Inelastic Thermal Spike Model to the Investigation of Damage Induced by High‐Energy Ions in Polymers

• Published in: Macromolecular chemistry and physics 2023-02, Vol.224 (4), p.n/a
• Main Authors: da Rocha, Maximiliano S., May, João Pedro M., Thomaz, Raquel S., Papaléo, Ricardo M., Toulemonde, Marcel
• Format: Article
• Language: English
• Subjects: Amorphization; Damage; Depolarization; Difluorides; Electron density; inelastic thermal spike; ion tracks; Polyethylene terephthalate; Polymers; Polymethyl methacrylate; Polyphenylene sulfides; radiation effects; Spikes (lattice defects); Thermal decomposition; Vinylidene
• ISSN: 1022-1352; 1521-3935
• DOI: 10.1002/macp.202200339

This work reports on damage production in polymers by high‐energy ions within the framework of the inelastic thermal spike model (i‐TS). The model is used to describe the effective size of the damaged region around the ion path (the track size) in amorphous poly(methyl methacrylate) (PMMA) and the semicrystalline poly(p‐phenylene sulphide) (PPS), poly(ethylene terephthalate) (PET), and poly(vinylidene difluoride) (PVDF). Track size calculations are compared to experimental data deduced from measurements of crater size, bond‐breaking cross‐sections, changes in crystallinity and electron density, track etching, and electrical depolarization. The use of data obtained from distinct types of damage provides a broad platform to test the applicability of the model to polymers. This work shows that the i‐TS correctly describes the dependence of the track size on energy loss obtained from most experimental probes, when the activation energy of thermal decomposition of the polymers is used as the criterion of track formation, using an electron–phonon mean free path of ≈3 nm. As damage is not uniform across the ion track radial dimension, there are fine variations in the experimental damage radii that can only be accounted for by using multiple activation processes. Amorphization radii of the semicrystalline polymers are not directly correlated to melting induced by the ions. Damage induced by energetic ions in polymers is analyzed using the inelastic thermal spike model. Calculations of the size of the damaged zone produced by individual ions in poly(methyl methacrylate) (PMMA), poly(ethylene terephthalate) (PET), poly(vinylidene difluoride) (PVDF), and PPS are compared to experimental data deduced from microscopy, X‐ray scattering, and spectroscopy techniques in a broad range of ion velocities and energy loss with very good agreement.