Highly Tunable Thiol-Ene Networks via Dual Thiol Addition

Throughout the past decade, investigations of thick thermoset thiol-ene networks (TENs) have become increasingly prominent in the literature due to facile, quantitative synthesis giving rise to unique network characteristics, specifically high mechanical energy damping. This article reports the synthesis and thermomechanical properties of ternary thiol-thiol-ene systems that exhibit tunable glass transitions that maintain high, narrow tan delta values in the glass transition region. We begin with a base network of a trifunctional thiol and a trifunctional ene and then systematically substitute the trifunctional thiol with a series of difunctional thiols while maintaining stoichiometric balance between total thiol and ene content. The resultant ternary networks exhibit glass transition temperatures that follow the Fox equation. In contrast to other ternary thiol-ene networks, we observe minimal broadening of the glass transition region, which implies that we can retain the energy-absorbing capabilities of the thiol-ene system. This approach has high potential as a simple tool for scientists and researchers to tune T(g)s for select networks without detrimentally affecting other physical properties.