Towards efficient initiators for two-photon induced polymerization: fine tuning of the donor/acceptor properties

Holzer, Brigitte; Lunzer, Markus; Rosspeintner, Arnulf; Licari, Giuseppe; Tromayer, Maximilian; Naumov, Sergej; Lumpi, Daniel; Horkel, Ernst; Hametner, Christian; Ovsianikov, Aleksandr; Liska, Robert; Vauthey, Eric; Fröhlich, Johannes

doi:10.1039/c8me00101d

Cited by 22 publications

(23 citation statements)

References 53 publications

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“…Recently, we have reported on the synthesis and photophysical properties of a series of cap–linker–cap systems based on substituted thiophenes bearing various triphenylamines with two-photon absorption maxima in the NIR and efficient two-photon initiation properties (verified by polymerization tests). 45 − 47 In this work, we expand on this previous design strategy to further increase the two-photon absorption and, thus, the efficiency of 2PA initiators based on quadrupolar cap–linker–cap type molecules.…”

Section: Introductionmentioning

confidence: 99%

Beyond the Threshold: A Study of Chalcogenophene-Based Two-Photon Initiators

et al. 2022

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A series of nine soluble, symmetric chalcogenophenes bearing hexyl-substituted triphenylamines, indolocarbazoles, or phenylcarbazoles was designed and synthesized as potential two-photon absorption (2PA) initiators. A detailed photophysical analysis of these molecules revealed good 2PA properties of the series and, in particular, a strong influence of selenium on the 2PA cross sections, rendering these materials especially promising new 2PA photoinitiators. Structuring and threshold tests proved the efficiency and broad spectral versatility of two selenium-containing lead compounds as well as their applicability in an acrylate resin formulation. A comparison with commercial photoinitiators Irg369 and BAPO as well as sensitizer ITX showed that the newly designed selenium-based materials TPA-S and TPA-BBS outperform these traditional initiators by far both in terms of reactivity and dose. Moreover, by increasing the ultralow concentration of TPA-BBS , a further reduction of the polymerization threshold can be achieved, revealing the great potential of this series for application in two-photon polymerization (2PP) systems where only low laser power is available.

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Section: Introductionmentioning

confidence: 99%

Beyond the Threshold: A Study of Chalcogenophene-Based Two-Photon Initiators

et al. 2022

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“…Indeed, substantial efforts have been dedicated to designing, synthesizing, and characterizing photoinitiator molecules exhibiting large two‐photon‐absorption cross sections at certain wavelengths. [ 23–35 ] However, it has become evident from recent detailed one‐photon‐absorption experiments [ 36 ] that the absorption spectrum versus wavelength may peak at a completely different wavelength than the spectrum of the corresponding light‐induced polymerization rate. [ 36,37 ] Importantly, this surprising and not‐well‐understood finding refers to optically thin samples.…”

Section: Introductionmentioning

confidence: 99%

Sensitive Photoresists for Rapid Multiphoton 3D Laser Micro‐ and Nanoprinting

Wegener

Hahn

Nardi

et al. 2020

Advanced Optical Materials

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parallel projection technologies, [6-8] computed axial lithography as an inverse tomography approach based on multiple 2D optical one-photon exposures from multiple different directions, [9,10] and different forms of multiphoton-absorption 3D printing, [11-16] mostly based on femtosecond or picosecond pulsed lasers. Twophoton lithography has been pioneered by Maruo et al. in 1997. [17] In a few exceptions, continuous-wave (cw) lasers have been used. [18,19] Going "faster" can mean scanning a single focus faster, [20] adapting multiple foci approaches, [21,22] scanning multiple foci faster, [3] or printing more voxels/ pixels in parallel per unit time in projection-based approaches without scanning in the focal plane, [6,7,9,10,12] yet scanning normal to the focal plane. In any case, increasing the printing rate is inherently connected to either using more laser power and the same photoresist, or to using comparable or less laser power by exploiting optimized more sensitive photoresists. As femtosecond or picosecond laser power is a precious commodity associated with a considerable fraction of the cost of most advanced 3D multiphoton laser printers, we dedicate the main part of this contribution to a screening of sensitive multiphoton-absorption-based photo resists. These photoresists are either taken from the published literature, reproduced and remeasured in our labs, or are newly investigated herein as promising candidates. Driven by recent advances in rapid multiphoton single-focus 3D laser nanoprinting, multifocus variants thereof, and projection-based multiphoton 3D laser nanoprinting, the necessary average total laser powers from femtosecond laser oscillators or even from amplified femtosecond laser systems have exceeded the Watt level. Aiming at ever faster 3D printing, there exist two options: Using yet more powerful lasers or searching for more sensitive photoresists allowing for higher speeds at comparable or lower power levels. Here, altogether more than 70 different photoresists from the literature and a few new candidates are reviewed with regard to effective multiphoton sensitivity. A dimensionless sensitivity figure-of-merit allows to directly compare data taken under sometimes vastly different conditions.

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“…Searching for new heterocycles with interesting acceptor properties, recently developed thiophene based compounds exhibit high σ TPA values [103–104] . By combining thiophene as a planar π‐linker with several electron rich triphenylamine donors, new 2PIs (Figure 46) with broad fabrication windows were obtained [105] …”

Section: D‐π‐a‐π‐d Chromophoresmentioning

confidence: 99%

From Light to Structure: Photo Initiators for Radical Two‐Photon Polymerization

Schubert

Wloka

Gottschaldt

2022

Chemistry A European J

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Two-photon polymerization (2PP) represents a powerful technique for the fabrication of precise threedimensional structures on a micro-and nanometer scale for various applications. While many review articles are focusing on the used polymeric materials and their application in 2PP, in this review the class of two-photon photo initiators (2PI) used for radical polymerization is discussed in detail. Because the demand for highly efficient 2PI has increased in the last decades, different approaches in designing new efficient 2PIs occurred. This review summarizes the 2PIs known in literature and discusses their absorption behavior under one-and twophoton absorption (2PA) conditions, their two-photon cross sections (σ TPA ) as well as their efficiency under 2PP conditions. Here, the photo initiators are grouped depending on their chromophore system (D-π-A-π-D, D-π-D, etc.). Their polymerization efficiencies are evaluated by fabrication windows (FW) depending on different laser intensities and writing speeds.

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Towards efficient initiators for two-photon induced polymerization: fine tuning of the donor/acceptor properties

Abstract: A study of two-photon polymerization initiators is presented.

Cited by 22 publications

References 53 publications

Beyond the Threshold: A Study of Chalcogenophene-Based Two-Photon Initiators

Beyond the Threshold: A Study of Chalcogenophene-Based Two-Photon Initiators

Sensitive Photoresists for Rapid Multiphoton 3D Laser Micro‐ and Nanoprinting

From Light to Structure: Photo Initiators for Radical Two‐Photon Polymerization

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