Wavelength-optimized two-photon polymerization using initiators based on multipolar aminostyryl-1,3,5-triazines
journal contributionposted on 04.12.2018 by Maximilian Tromayer, Peter Gruber, Arnulf Rosspeintner, Aliasghar Ajami, Wolfgang Husinsky, Felix Plasser, Leticia Gonzalez, Eric Vauthey, Aleksandr Ovsianikov, Robert Liska
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Two-photon induced polymerization (2PP) based 3D printing is a powerful microfabrication tool. Specialized two-photon initiators (2PIs) are critical components of the employed photosensitive polymerizable formulations. This work investigates the cooperative enhancement of two-photon absorption cross sections (σ2PA) in a series of 1,3,5-triazine-derivatives bearing 1-3 aminostyryl-donor arms, creating dipolar, quadrupolar and octupolar push-pull systems. The multipolar 2PIs were successfully prepared and characterized, σ2PA were determined using z-scan at 800 nm as well as spectrally resolved two-photon excited fluorescence measurements, and the results were compared to high-level ab initio computations. Modern tunable femtosecond lasers allow 2PP-processing at optimum wavelengths tailored to the absorption behavior of the 2PI. 2PP structuring tests revealed that while performance at 800 nm is similar, at their respective σ2PA-maxima the octupolar triazine-derivative outperforms a well-established ketone-based quadrupolar reference 2PI, with significantly lower fabrication threshold at exceedingly high writing speeds up to 200 mm/s and a broader window for ideal processing parameters.
The authors acknowledge the financial support by the Austrian Science Fund (FWF): P 27555, TU Wien, the University of Vienna and the Universite de Geneve.