"Two-photon microprinting: from innovative photoinitiators to hybrid materials" by Akos Banyasz

Seminar by Akos Banyasz, CNRS Researcher, Laboratoire de Chimie École Normale Supérieure de Lyon

Abstract

Additive manufacturing promises to revolutionize industry. Among the various methods two-photon induced microprinting or direct laser writing has a prominent role due to its high resolution and relatively low cost. However, fabrication of high-resolution and large objects with specific physical properties remains a critical challenge and needs innovation in both chemical processing and 3D-printing techniques.

To address these challenges, we have recently undertaken the development new highly sensitive photoinitiators for radical polymerization. These compounds benefiting from the near-resonance enhancement of the two-photon absorption due to the proximity of the irradiation wavelength to the one-photon absorption band. Once incorporated into suitable formulations, such photoinitiators enable to increase the fabrication throughput while maintaining sub-micron resolution.

Sol-gel technology, a versatile chemical process, facilitates the preparation of hybrid and inorganic materials under mild conditions. Diverse morphologies can be synthesized via acid- or base-catalyzed hydrolysis-condensation reactions using alkoxide precursors. Furthermore, the incorporation of specific moieties in these materials results in customized properties. Today, hybrid materials combined with 3D printing are responding to the increasing demand of the industry for novel functional materials.

We used a specifically designed organosilane-based hybrid resin enabling a dual fabrication strategy using both UV maskless projection lithography and two-photon direct laser writing. The combination of a radical photoinitiator and a photobase generator in the resin allows to trigger both radical polymerization and condensation reactions, as evidenced by infrared microspectroscopy. The proposed approach produces both large area and high-resolution 3D structures upon one- and two-photon absorption induced polymerization, respectively. This new paradigm may pave the way towards the efficient fabrication of microfluidics and microoptics.

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