Facilitating Polylactide’s End-of-Life: Nutrient-Loaded Silica Nanoparticles Enhance Environmental Biodegradation in Bulk and in 3D-Printed Structures

The intrinsically slow biodegradation of poly(lactic acid) (PLA) limits its environmental benefits. Here, we present an effective strategy to accelerate PLA’s biodegradation by preparing nanocomposites with nutrient-loaded silica nanoparticles (YMG-SiNPs), synthesized via sol–gel chemistry in an inverse microemulsion. These nanoparticles, containing a microbial growth medium of yeast extract, malt extract, and glucose (YMG), promote microbial colonization and enhance matrix degradation. Through surface grafting of short-chain PLA, YMG-SiNPs were well dispersed into both amorphous PLA and semicrystalline PLLA matrices, effectively preventing nanoparticle aggregation and mostly preserving the mechanical properties of the base polymer. The resulting nanocomposites demonstrated accelerated biodegradation in compost, showing up to 53% higher mass loss for amorphous PLA-A1 (containing 10 wt % YMG-SiNPs) compared to neat PLA-A1 after 21 days, and 20% increased mass loss for semicrystalline PLLA-C1 (containing 10 wt % YMG-SiNPs) after 28 days under industrial composting conditions (58 °C). Notably, YMG–SiNP-loaded semicrystalline PLLA remained compatible with standard FDM 3D printing, with printed structures exhibiting 44% higher mass loss (56% remaining) after 14 days of composting compared with neat 3D-printed PLLA-C2 (90% remaining). This work provides a scalable platform for designing compostable polymers with tunable degradation profiles, significantly advancing the development of sustainable materials with improved end-of-life behavior and expanded applications, including additive manufacturing.