On‐Demand Editing of Surface Properties of Microstructures Made by 3D Direct Laser Writing via Photo‐Mediated RAFT Polymerization

Abstract

Recently, photo-controlled reversible addition-fragmentation chain transfer (RAFT) polymerization has been successfully applied in digital light processing 3D printing. It provides a convenient way to tune the surface properties of the 3D printed object. However, so far, 3D micro-and nanostructures and reconfigurations based on photo-induced RAFT polymerization have not been presented. In this work, one macro-photoiniferter, synthesized by photocontrolled RAFT polymerization is applied, to 3D direct laser writing. Thanks to the exquisite spatial control of the photoreaction, 3D microstructures with feature sizes of around 500 nm are successfully obtained. Taking advantage of the presence of dormant polymeric RAFT agents, photo-induced postmodification of the printed microstructures is highlighted via the elaboration of multi-chemistry patterns including thermo-responsive ones. These results open new perspectives in multi-material and 4D micro-printing.

Application of RAFT in 3D Printing: Where Are the Future Opportunities?

“…Since it was initially published, − the field of RAFT-mediated 3D printing has rapidly developed and expanded beyond the creation of reprocessable/living 3D materials. ,, This technology has been utilized in cutting-edge applications such as self-healing polymers, surface patterning, nanostructuration, , and customized drug delivery . To accomplish these applications, several chemical mechanisms such as photoiniferter (direct photolysis), , photoinduced electron/energy transfer (PET)-RAFT, , cationic RAFT, , and photoinitiator RAFT , have been utilized.…”

A general photoiniferter approach to the surface functionalization of acrylic and methacrylic structures written by two-photon stereolithography

“…RDRP) in order to re-start the polymerization for tuning the surface properties as reported, for instance, by Spangenberg and co-workers. 58 However, these approaches are not particularly versatile for the fabrication of polymeric nano/microstructures as every photoresin ( i.e. its specific chemical composition) will require the optimization of the writing parameters ( e.g.…”

RAFT-Mediated 3D Printing of “Living” Materials with Tailored Hierarchical Porosity

“…Nevertheless, to address the limitations of conventional nonliving radical polymerization, our group − and others − have exploited reversible addition–fragmentation chain-transfer (RAFT) polymerization to endow “living” character to the 3D-printed materials. The “living” character of the 3D materials is offered by the incorporated RAFT functionalities within the constituting structure of 3D materials that are capable of reversibly deactivating the propagating polymer chains. , The dormant RAFT species can be reactivated (thermally or under light exposure) in a post-printing stage to allow spatiotemporal insertion of new monomers/polymers into the strands of existing 3D polymers, surface functionalization, ,, welding/self-healing, , and/or expansion of an already fabricated material. − From the viewpoint of sustainability and recyclability, materials that can undergo controlled changes in a post-printing stage can address the challenges associated with 3D-printed waste polymers and pave the way for future advancements and scaling-up of the 3D technology.…”

“…More recently, controlled degradation of thioester-containing 3D-printed materials was also demonstrated via base-catalyzed thiol-thioester exchange . The application of photoRAFT in 3D direct laser writing (DLW) has been recently reported, where the surface of RAFT-containing 3D materials could be precisely patterned in a post-printing stage via reactivation of dormant RAFT species . Cationic RAFT polymerization has also been reported to be effective in 3D printing living materials under broad wavelengths from ultraviolet (UV) to near-infrared (NIR) light …”

“…55 The application of photoRAFT in 3D direct laser writing (DLW) has been recently reported, where the surface of RAFT-containing 3D materials could be precisely patterned in a post-printing stage via reactivation of dormant RAFT species. 27 Cationic RAFT polymerization has also been reported to be effective in 3D printing living materials under broad wavelengths from ultraviolet (UV) to near-infrared (NIR) light. 29 All of the abovementioned research studies have shown the versatility of RAFT-mediated 3D printing.…”