S. Schlögl, M.-L. Trutschel, W. Chassé, I. Letovsky-Papst, R. Schaller, A. Holzner, G. Riess, W. Kern, K. Saalwächter.
Photo-vulcanization using thiol-ene chemistry: Film formation,
morphology and network characteristics of UV crosslinked rubber
Polymer 55, 5584-5595 (2014).
The photo-vulcanization with versatile thiol-ene chemistry represents an innovative approach to
crosslink diene-rubber materials both in latex and in solid film state. In this work, the structure of
elastomer-based thiol-ene networks and the morphology after film formation are studied in detail using
electron microscopic techniques, atomic force microscopy and multiple-quantum solid-state NMR
spectroscopy. Additionally, film formation properties and corresponding macroscopic properties of
photo-vulcanized natural rubber (NR) latex and its synthetic counterpart, isoprene rubber (IR) latex, are
determined in dependence on the curing procedure (pre- and post-vulcanization). The results reveal that
thiol-ene cured elastomers comprise homogenously distributed crosslinks with a low amount of short
chain defects. Whilst photochemically pre-cured NR latex particles provide coherent films, the film
formation and mechanical properties of IR are strongly governed by the crosslink density of the latex
particles. In film state, photo-vulcanization promotes narrow crosslink distributions and excellent tensile
properties of both NR and IR.