Dresden 2006 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 27: POSTER Polymer Physics and Materials

CPP 27.36: Poster

Thursday, March 30, 2006, 17:00–19:00, P2

Ion Irradiation of Polystyrene - Sol Molecular Weight Distribution — •Ralf Delto and Rüdiger Brenn — Physikalisches Institut, Universität Freiburg, Hermann-Herder-Str.3, 79104 Freiburg

Irradiation of polymers with high energetic ions results in a change of molecular weight distribution. The formation of crosslinks produces a gel fraction (network) while breaking of chains leads to a soluble sol fraction. The change of the Mw distribution depends on the applied ion dose.

Theoretical and experimental work has been done on the production of networks. Here we concentrate on the sol part. Sol-Mw distributions are calculated with statistical methods and with numerical simulations. Measurements are performed on polystyrene (PS) thin films using 1 MeV protons for irradiation. The films consist of a deuterated and a protonated layer (dPS-hPS). The irradiated sol (dPS and hPS) diffuses into the opposite layer while heating above Tg. As the tracer diffusion constant depends on the molecular weight, chains of different length diffuse unequally fast. Thus the diffusion profiles contain information about the abundance of chains of different degrees of polymerisation in the sol. Diffusion depths profiles for the deuterated component are determined with 3He nuclear reaction analysis.