Tailoring Interfacial Interactions via Polymer-Grafted Nanoparticles Improves Performance of Parts Created by 3D Printing

Decorating nanoparticle surfaces with end-tethered chains provides a way to mediate interfacial interactions in polymer nanocomposites. Here, polymer-grafted nanoparticles are investigated for their impact on the performance of polymer structures created by fused filament fabrication (FFF). The nanoscale organization of poly(methyl methacrylate)-grafted nanoparticles (PMMA-g-NPs) in PMMA matrices is examined via small-angle X-ray scattering (SAXS). SAXS data indicate that all nanocomposites exhibit particle–particle interactions, indicating that nanoparticles are locally clustered. Additionally, increasing the loading level of PMMA-g-NPs produces modest changes in Tg but significant increases in the complex viscosity and storage modulus, suggesting that the number density of entanglements between graft chains and the matrix polymer increases with increasing PMMA-g-NP content. Increasing the number density of entanglements and the formation of localized clusters manifest at the macroscale: Dynamic mechanical analysis and tensile testing show that FFF-printed PMMA-g-NPs/PMMA nanocomposites display a 65% increase in the Young’s modulus, 116% increase in the ultimate tensile strength, and a 120% increase in the storage modulus compared to parts printed with pure (unfilled) PMMA. This research effort highlights how interfacial engineering can be used to enhance interactions on the nanoscale and improve the macroscopic properties of parts printed by FFF.