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Material development is key for continuing the exponential growth in the field of 3D printing. However, 3D printing of polymers by laser powder bed fusion (PBF‐LB) still is limited to a few polymer powder materials, which restricts the range of applications. Tailoring the chemical, rheological, mechanical, or optical properties of the feedstock powder to the requirements of the laser printing process poses a significant challenge. In order to meet global trends in the commercialization of desktop 3D printers, the use of inexpensive and compact diode lasers for PBF‐LB in the visible or near‐infrared range is highly desired. However, at present, only black objects can be printed by desktop laser printers since only commercial carbon black‐based composite powders meet their laser absorption requirements. In this study, a route for tuning the absorption properties of thermoplastic polyurethane polymers and incorporating color into printed objects by using minute amounts (i.e., 0.01 vol%) of highly dispersed plasmonic silver nanoparticles is reported, presenting a new way for colored parts to be produced through laser 3D printing.

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No unified model is available yet to explain the dynamics of laser-induced cavitation bubbles during laser ablation of solid targets in liquids, when an extremely high capillary number is achieved (>100), i.e. when the viscous forces strongly contribute to the friction. By investigating laser-induced bubbles on gold and yttrium iron garnet targets as a function of the liquid viscosity, using a nanosecond laser and an ultrafast shadowgraph imaging setup, we give a deeper insight into what determines the bubble dynamics. We find that the competition between the viscous forces and the surface tension (capillary number Ca), on the one hand, and the competition between the viscous forces and inertia (Reynolds Number Re), on the other hand, are both key factors. Increasing the viscous forces and hereby Ca up to 100 has an impact on the bubble shape and result in a very pronounced rim, which separates the bubble in a spherical cap driven by inertia and an interlayer. The temporal evolution of the footprint radius of the interlayer can be addressed in the framework of the inertiocapillary regime. For an intermediate viscosity, the thickness of the interlayer is consistent with a boundary layer equation.Interestingly, our data cannot be interpreted with simplified hydrodynamic (Cox-Voinov) or molecularkinetic theory models, highlighting the originality of the dynamics reported when extremely high capillary numbers are achieved. Upon bubble collapse, spherical persistent microbubbles are created and partly dispersed in water, whereas the high-viscous polyalphaolefines lead to long-standing oblate persistent bubbles sticking to the target´s surface, independent of the ablated target. Overall, liquid´s viscosity determines laser ablation-induced cavitation.