NMR study of the gamma radiolysis of poly(dimethyl siloxane) under vacuum at 303 K |
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Authors: | David JT Hill Christopher ML PrestonAndrew K Whittaker |
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Affiliation: | a Polymer Materials and Radiation Group, Department of Chemistry, The University of Queensland, Brisbane, Qld 4072, Australia b Centre for Magnetic Resonance, The University of Queensland, Brisbane, Qld 4072, Australia |
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Abstract: | The structural changes which occur on the γ-radiolysis of poly(dimethyl siloxane) (PDMS) under vacuum at 303 K have been investigated using 29Si and 13C NMR. New structural units consistent with main chain scission and crosslinking through both H-linking and Y-linking reactions have been identified. The results obtained at various absorbed doses have been used to calculate the G-values for scission and crosslinking. G-values for scission of G(S)=1.3±0.2, for H-linking of G(DCH2-R)=0.34±0.02 and for Y-linking of G(Y)=1.70±0.09 were obtained for radiolysis under vacuum at 303 K. Thus crosslinking predominates over scission for radiolysis of PDMS under these conditions, and, by contrast with previous studies, Y-links have been shown to be the predominant form of crosslinks. |
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Keywords: | Poly(dimethylsiloxane) 29Si & 13C solid-state NMR γ-Radiolysis |
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