(649e) Directed Printing and Reconfiguration of Thermoresponsive Silica-Pnipam Nanocomposites

Printing of polymeric composites into desired patterns and shapes has revolutionized small scale manufacturing processes. However, directed high-resolution printing of adaptive materials that change shape in response to external stimuli remains a significant technical challenge. The work presents a new approach of printing thermoresponsive poly(N-isopropylacrylamide) into macroscopic structures that dynamically reconfigure in response to heating and cooling cycles. The printing process is performed using an external laser source, which enables thermal crosslinking of the polymer ink consisting of monomer, cross-linker, initiator, and inorganic nanoparticles. It is shown that the addition of silica nanoparticles enhances the mechanical properties of poly(N-isopropylacrylamide) while maintaining its thermoresponsiveness at micrometer scale resolution, which otherwise is not feasible by extrusion-based 3D printing techniques. It is demonstrated that spatial reconfiguration of the printed monolayers upon increasing temperature is governed by the local geometry, which enables mimicking the reconfiguration of plant leaves in natural environment. The study lays a foundation for developing a new fabrication platform to print thermoresponsive structures which may find potential applications in biomedical implants, sensors, and other multi-responsive materials.