Novel POSS-Cerium Oxide Thermoset Nanocomposites For UV Degradation Mitigation

Mechanical and thermal properties of microchannel insulating foams comprising a multifunctional epoxy/polyhedral oligomeric silsesquioxane nanocomposite

“…In fact, Strachota et al states modulus is not dependent upon POSS content as long as the crosslink density remains constant 11 . Other reports have included data on the flexural strength and moduli, 16,46,62,67 tensile strength and moduli, 6,17,46,62,66 and impact strength of POSS nanocomposites 16,17,62,65 . In work by Sethuraman et al, the flexural and impact strength of solid epoxy/POSS samples were found to improve approximately 8% to 18% at POSS loadings of less than 3 wt% due to increased toughness associated with the flexible POSS chain functionalities, but then drop at higher POSS loadings due to increased aggregation/poor dispersion 62 .…”

“…The silica‐rich regions may serve as load stress modifiers, with good adhesive forces between chain segments enhancing the overall material strength 62 . Piness et al suggests the ultimate strength is affected more by the compatibility of the POSS functional group with the matrix resin, not the actual POSS loading level 46 . Additionally, since the modulus depends primarily on crosslink density and we used stoichiometric quantities of DDS for each resin recipe, the stiffness is relatively unaffected by the changing POSS content (Figure 5B).…”

“…Recent literature reports suggest significant improvements in AO and UV stability have been successfully implemented using a variety of ceramic‐based additives. Research has reported on these additives dispersed uniformly within the polymer volume 5,6 and/or as a thin composite/nanocomposite protective oxide coating at the exposed outer surface 7 . These strategies commonly employ silica‐based additives, with increasingly smaller particulates showing improved environmental durability, thermal stability, and/or mechanical properties of the resin system due to the increase in specific surface area of the well‐dispersed nano‐additives 5–10 .…”

“…These foams contain pore structures in the form of hollow microchannels with engineered microchannel orientations created via extraction of thermoplastic templating fibers after curing of the infused thermosetting epoxy resin (for reference, these materials are shown in Figure 2). Based on literature reports, addition of POSS to the epoxy‐based foam matrix is anticipated to not only improve the thermal stability 25 and mechanical performance, 45 but also the resistance to UV degradation 5–7,46–52 . However, given the wide range in reported properties of the polymer‐POSS composites for both improved dielectric properties and increased conductivities, it is unclear how the presence of the POSS particulates contained in the foam matrix volume will impact the thermal conductance in the foam struts and filaments.…”

“…Research has reported on these additives dispersed uniformly within the polymer volume 5,6 and/or as a thin composite/nanocomposite protective oxide coating at the exposed outer surface 7 . These strategies commonly employ silica‐based additives, with increasingly smaller particulates showing improved environmental durability, thermal stability, and/or mechanical properties of the resin system due to the increase in specific surface area of the well‐dispersed nano‐additives 5–10 . In particular, hybridized inorganic‐organic silica‐polymer nanomaterials based on polyhedral oligomeric silsesquioxane (POSS) have shown excellent potential not only in improving mechanical properties 10–17 and thermal stability 10,11,14–16,18–23 but also for enhanced dielectric performance, 15,16,24–28 flammability resistance, 29–31 catalysis, 32 electrolytic capabilities, 33–35 thermal and electrical conductivities, 26,28,36 abrasion resistance, 10,16 shape memory polymer behavior, 37 liquid crystals and sensors, 22,38 and froth flotation surfactants, 39 among others.…”