Crosslinked polymeric networks have been utilized as effective building blocks for the development of a variety of multifunctional materials in materials science, nanoscience, and industrial fields. Here, we report thiol-ene polysulfide-crosslinked polymethacrylate networks reinforced with aluminum oxide nanoparticles (ALNPs) prepared by photo-induced thiol-ene radical addition for reactive blends consisting of functional polymethacrylates having pendant vinyl and SH groups with different molecular weights in the presence of ALNPs. Various techniques including viscoelastic measurement, nano-scratch test, differential scanning calorimetry, and thermogravimetric analysis allow for elucidating the effect of ALNPs on the properties of thiol-ene crosslinked films. Analysis of these results, combined with optical and scanning electron microscopy, suggests that the introduction of an optimal amount of ALNPs and the design of relatively low molecular weight polymethacrylates resulted in enhanced scratch resistance and thermal stability of thiol-ene sulfide-crosslinked networks. (C) 2016 Elsevier Ltd. All rights reserved.