Monte Carlo study of molecular weight distribution changes induced by degradation of ion beam irradiated polymers

V.C. CHAPPA; C. P ASTORINO; M. F. DEL GROSSO; C. R. ARBEITMAN; M. MÜELLER; G. GARCÍA BERMÚDEZ

NUCLEAR INSTRUMENTS AND METHODS IN PHYSICS RESEARCH B - BEAM INTERACTIONS WITH MATERIALS AND ATOMS

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2010 vol. 268 p. 3235 - 3238

0168-583X

In this work we study a polymeric material that degrades upon irradiation due to the energy inhomogeneously deposited byheav y ion beams. Ion beam irradiation of polymers generates rather dierent eects than those induced by “ classical” low ioniz ingparticles such as electrons or gamma rays. This is due to the high electronic stopping power and the inhomogeneous distribution ofdeposited energy. This energy is transferred to the material within a small v olume along the ion path forming the so called “ nucleartrack ” or “ latent track ” . The track siz e primarily depends on the ion v elocity, and it is determined by the secondary electrons (deltarays) generated along the ion trajectory. By means ofMonte Carlo simulations we rst obtained eq uilibrated polymer congurationsusing a coarse-grained model, and then inv estigated the spatially inhomogeneous chain scission process due to the passage of theions. The number av erage molecular weight, weight av erage molecular weight and the polydispersity were calculated as a functionof track radius, scission probability within the ion track and irradiation uence. Finally we compared our results with a numericalimplementation of a model for random homogeneous degradation.