Due to the pronounced effects of crystallinity on the storage modulus observed in DMA and the excellent homogeneous and complete curing behavior of the bulk specimens, we anticipated excellent thermomechanical performance of these materials. Further tests exclude the comonomers TEMPIC and TMPMP as they result in a relatively unremarkable storage modulus progression and low crystallinity. Indeed, tensile tests reveal high tensile strength of around 19 MPa for the polymer employing pure CHTT as the comonomer (Figure ). However, the high degree of crystallinity paired with a rigid network matrix causes brittle fracture at around 4% elongation. Conversely, using ETTMP as the exclusive comonomer results in a low tensile strength with a lower elongation at break than the specimen containing only 20% thiol end groups of ETTMP. When attempting to toughen the polymer by tuning the network density through substitution of CHTT with 10 mol% ETTMP, the tensile strength decreases but the elongation at break triples. Addition of 20 mol% ETTMP hardly affects the yield strength of the material compared to 10 mol% while massively improving the elongation at break to 200%. Together with the pronounced yield point and necking of the specimen, this photopolymer network remarkably resembles thermoplastic behavior.