Reversible Optical Data Storage via Two-Photon Micropatterning of o‑Carboranes-Embedded Switchable Materials

Abstract

Two-photon polymerization (2PP) constitutes a powerful light-triggered 3D stereolithography, allowing the fabrication of micro- or nanostructures with spatially encoded functionalities. In the present report, we take advantage of this programmable property in order to develop a photoresist authorizing the direct 2PP-lithography of luminescent switchable μ-structures. In this single step processing method, we highlight the pivotal role of a quadrupolar o-caborane initiator comprising a 9, 10-disubstituted anthracene core capable of chemically entrap oxygen-inhibiting species during the free radical two-photon initiation step. Such an O2 sequestration approach not only enhances the two-photon initiation performance of the polymerization, but also generates a non-luminescent endoperoxide by-product embedded in the polymerized macrostructure. Interestingly, simple heating of the final materials promotes endoperoxide thermolysis, resulting in the recovery of the luminescent o-carborane dye. This original luminescence turn OFF/ON property exhibits excellent fatigue resistance through a large number of alternated thermal and light stimuli cycles. The potential of this direct laser writing strategy for reversible data storage applications is finally demonstrated by the two-photon patterning of a series of matricially organized μ-structures used as rewritable binary optical memories which can be easily encoded on demand.