Two-Photon Laser Writing of Soft Responsive Polymers via Temperature-Controlled Polymerization

Enhancing the resolution of 3D patterning techniques in functional soft polymers enlarges the application areas of responsive shape-changing materials, for tunable nanophotonics and nanorobotics. Thanks to the recent advances of polymer science, the palette of available materials for nanomanufacturing is becoming wider and wider--although the comprehension of their polymerization process by two-photon polymerization is still incomplete. In this work, both shrinking of the minimal polymerizable unit and a significant improvement of the mechanical stability of microstructured soft polymers, in particular of liquid crystalline networks, are demonstrated. To this aim, temperature control enhances the resolution and reduces the swelling of the polymerized structures, thus avoiding deviations of the final structure from the intended design. This fine control on the nanoscale features enables the use of soft responsive materials not only for bulky microelements, but also for high-resolution structures with more complex design.