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

Two-photon polymerization (2PP) constitutes a powerfullight-triggered3D stereolithography, allowing the fabrication of micro- or nanostructureswith spatially encoded functionalities. In the present report, wetake advantage of this programmable property in order to develop aphotoresist authorizing the direct 2PP-lithography of luminescentswitchable & mu;-structures. In this single step processing method,we highlight the pivotal role of a quadrupolar o-caborane initiator comprising a 9, 10-disubstituted anthracene corecapable of chemically entrap oxygen-inhibiting species during thefree radical two-photon initiation step. Such an O-2 sequestrationapproach not only enhances the two-photon initiation performance ofthe polymerization, but also generates a non-luminescent endoperoxideby-product embedded in the polymerized macrostructure. Interestingly,simple heating of the final materials promotes endoperoxide thermolysis,resulting in the recovery of the luminescent o-carboranedye. This original luminescence turn OFF/ON property exhibits excellentfatigue resistance through a large number of alternated thermal andlight stimuli cycles. The potential of this direct laser writing strategyfor reversible data storage applications is finally demonstrated bythe two-photon patterning of a series of matricially organized & mu;-structuresused as rewritable binary optical memories which can be easily encodedon demand.