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Microstructural PALS study of regulated dimethacrylates: Thiol- versus -allyl sulfone-based networks
Verfasser / Verfasserin Švajdlenková, Helena ; Šauša, Ondrej ; Steindl, Johannes ; Koch, Thomas ; Gorsche, Christian
Erschienen in
Journal of Polymer Science, 2016, Jg. 54, H. 24, S. 2476-2484
ErschienenWiley, 2016
SpracheEnglisch
DokumenttypAufsatz in einer Zeitschrift
Schlagwörter (EN)addition fragmentation chain transfer / Mc value / photopolymerization / positron annihilation / structure-property relations
Projekt-/ReportnummerAustrian Science Fund (FWF): P27059
ISSN1542-9385
URNurn:nbn:at:at-ubtuw:3-5384 Persistent Identifier (URN)
DOI10.1002/polb.24240 
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Microstructural PALS study of regulated dimethacrylates: Thiol- versus -allyl sulfone-based networks [1.33 mb]
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Zusammenfassung (Englisch)

Radical photocuring of multifunctional (meth)acrylates is lacking control over the irregular chain growth process yielding highly crosslinked, inhomogeneous networks. Chain transfer agents (CTAs, e.g. thiols or -allyl sulfones) have been widely used to modify this curing process, thus reducing shrinkage stress and increasing the toughness of the formed photopolymers. Resulting photopolymer networks exhibit higher bulk density, lower crosslinking density and narrow glass transitions. Consequently, a more homogeneous network structure was postulated for those networks. Whereas macroscopic properties of the modified final materials have already been studied, herein the microstructural arrangement of such modified networks has also been evaluated with the help of positron annihilation lifetime spectroscopy (PALS). A more homogenous network structure with a decreased free-volume void size was confirmed for CTA-based dimethacrylate networks. A sharper distribution of the orthopositronium (o-Ps) lifetime, mainly for the -allyl sulfone-based photopolymers, hints towards a more regulated network structure. Moreover, the combination of PALS, DMTA, density and swelling experiments elucidates relations between void formation, crosslinking density and macroscopic characteristics such as shrinkage stress and mechanical properties.

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