Impact of Shape Transformation of Programmable 3D Structures on UV Print Quality.

The field of 3D and 4D printing is advancing rapidly, offering new ways to control the transformation of programmable 3D structures in response to external stimuli. This study examines the impact of 3D printing parameters, namely the UV ink thickness (applied using a UV inkjet printer on pre-3D-printed programmable structures) and thermal activation, on the dimensional and surface changes to high-stress (HS) and low-stress (LS) programmable samples and on print quality. The results indicate that HS samples shrink in the longitudinal direction, while expanding in terms of their height and width, whereas LS samples exhibit minimal dimensional changes due to lower programmed stress. The dynamic mechanical analysis shows that UV ink, particularly cyan and CMYK overprints, reduces the shrinkage in HS samples by acting as a resistive layer. Thicker ink films further reduce the dimensional changes in HS samples. Thermal activation increases the surface roughness of HS structures, leading to the wrinkling of UV ink films, while LS structures are less affected. The surface gloss decreases significantly in HS structures after UV ink application; however, thermal activation has little impact on LS structures. UV ink adhesion remains strong across both HS and LS samples, suggesting that UV inks are ideal for printing on programmable 3D structures, where the colour print quality and precise control of the shape transformation are crucial.