4D-printable thermo- and light-responsive triple-shape memory polymer nanocomposites containing titanium nitride nanoparticles

In this work, novel light-responsive nanocomposites were developed by incorporating varying amounts (1-3-5 phr) of titanium nitride nanoparticles (TiN-NP) into a ternary polymer blend consisting of 30 wt% of maleic anhydride grafted SEBS (SEBS-MA), 40 wt% of ethylene vinyl acetate copolymer (EVA), and 30 wt% of butyl methacrylate/isobutyl methacrylate copolymer (PBMA-PiBMA), that exhibits thermally induced triple-shape memory properties. In the nanocomposite containing 1 phr TiN nanoparticles (1-TiN), a core-shell morphology was observed, with the fillers selectively localizing within the SEBS-MA phase. The presence of TiN filler did not have a significant effect on the thermal transition temperatures of the polymer components. An increase in TiN content resulted in enhanced elastic modulus values for the composites, with a notable 138 % rise observed in the composite that included 5 phr filler relative to the blend. The best heat responsive shape memory performance was observed in the 1-TiN composite, with the first and second shape fixation ratios of 91.6 % and 83.4 %, respectively, and the first and second shape recovery ratios of 90.8 % and 100 %, respectively. The 1-TiN composite underwent photothermal heating under 808 nm NIR light, reaching 40 degrees C and 80 degrees C at light intensities of 48 mW/cm2 and 158 mW/cm2, respectively, demonstrating light-responsive triple-shape memory effect. The filament of the same nanocomposite was produced, and 4D-printed objects were created using an FDM-type 3D printer for various applications. Moreover, the 4D-printed objects fabricated using the nanocomposite filament exhibit triple-shape recovery under NIR light with an intensity of 48 mW/cm2 and 161 mW/cm2.