Reaction Mechanisms and In Situ Process Diagnostics

Mueller, Jonathan B.; Fischer, Joachim; Wegener, Martin

doi:10.1016/b978-0-323-35321-2.00005-4

Cited by 9 publications

(4 citation statements)

References 25 publications

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“…expected due to excess energy of polymerization reaction. Surprisingly, the same tendency was observed independently on pulse repetition rate, which was varied in a wide range (1 kHz -80 MHz) (Mueller et al, 2016).…”

Section: Local Temperature Changes During the Dlw 3d Nano-polymerizationsupporting

confidence: 58%

Processes of Direct Laser Writing 3D Nano-Lithography

Varapnickas¹,

Malinauskas²

2018

Preprint

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Direct laser writing three-dimensional nano-lithography is an established technique for manufacturing functional 3D micro- and nano-objects via non-linear absorption induced polymerization process. In this Chapter an underlying physical mechanisms taking place during nano-confined polymerization reaction, induced by tightly focused ultra-short laser pulses, are reviewed and discussed. The specialattention is paid on the effects that directly impact structuring resolution and minimum achievable feature size. Analysis of possible photo-initiation mechanisms as contributing multi-photon absorption and avalanche ionization in pre-polymers under diverse exposure conditions (wavelength, pulse duration) is presented. Feasible structuring of pure (non-photosensitized) and functional nanoparticles doped polymer precursors is justified and benefits of such materials/structures for microoptics, photonics and cell scaffolds are highlighted. The influence of temperature effects (induced by writing process itself or determined by ambient conditions) on polymerization process, observed in different pre-polymers under diverse exposure regimes is outlined. The further adjustment of the structuring resolution is possible via precise control of light polarization and diffusion assisted radical quenching. The work is concluded with a brief outlook on future challenges and perspectives related to refinement of 3D ultra-fast laser lithography fabrication process in the means of application of diverse post-processing methods and research into novel photo-curable materials including inorganic ones.

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Section: Local Temperature Changes During the Dlw 3d Nano-polymerizationsupporting

confidence: 58%

Processes of Direct Laser Writing 3D Nano-Lithography

Varapnickas¹,

Malinauskas²

2018

Preprint

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“…The former is due to ionization and/or the excess heat of the photothermal process, which can vaporize the solvents present in the resist. [19][20][21][22] Both thresholds also appear as boundaries for the measurable DC.…”

Section: Two-photon Polymerization Lithographymentioning

confidence: 99%

Characterization of two-photon-polymerization lithography structures via Raman spectroscopy and nanoindentation

Schweiger

Schulze

Schlipf

et al. 2022

J. Optical Microsystems

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Additive manufacturing using two-photon polymerization (TPP) lithography is increasingly used in industry and research. Parameter sweeps of cuboid structures fabricated using TPP lithography were investigated across the parameters of the laser power and scan speed to find dependent mechanical material properties. The employed photoresists were examined using Raman spectroscopy to find the degree of conversion (DC) of monomer to polymer, and subsequently, micro-or nanoindentation was used to find Young's modulus (E). For the photoresist IP-Dip, the attained DC and E ranged from 20% to 45% and 1 to 2.1 GPa, respectively. The results were compared with reports found in the literature. For IP-Q, the attained DC and E ranged from 53% to 80% and 0.5 to 1.3 GPa, respectively. The characterized properties of IP-Q manifest as the current state of knowledge of the material.

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“…Thanks to this effect, the effective voxel size is reduced with respect to the expected one since part of the volume occupied by the QDs is lost. Thus, we are able to print spots whose size is close to 100 nm, considerably smaller than the results in the literature. ,, Therefore, by increasing the concentration of QDs, smaller voxels can be obtained. On the other hand, some few QDs remain trapped inside and get excited during TPP-DLW, so heat is released and it triggers the thermal polymerization of the surrounding photoresist, increasing the volume of the voxel.…”

Section: Resultsmentioning

confidence: 74%

Three-Dimensional Photoluminescent Crypto-Images Doped with (CdSe)ZnS Quantum Dots by One-Photon and Two-Photon Polymerization

Ritacco

Lio

et al. 2021

ACS Appl. Nano Mater.

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Three-dimensional (3D) photoluminescent crypto-images can be created by nanopatterning quantum dots (QDs) within a polymeric micro-object. A UV-sensitive photoresist, doped with (CdSe)ZnS core−shell QDs, is employed to fabricate fluorescent devices, by two-photon polymerization direct laser writing (TPP-DLW). In this work, we report on the expulsion of the majority of QDs from the irradiated area, caused by the crosslinking of the monomers, determining their accumulation on the photopolymer surface. At the same time, QDs get excited and trigger a surrounding thermal polymerization, leading to a variation of the spatial resolution of the fabricated structures. By opportunely combining these physical phenomena, it is possible to control the local density of QDs with nanometric resolution and, as a consequence, to tune the local photoemission of the fabricated polymeric structure. A photopolymer doped with five different concentrations of (CdSe)ZnS core−shell QDs is analyzed and tested. We define the best conditions to create nanostructures containing only few QDs to be integrated in optical devices, as well as to create 3D photoluminescent micro crypto-images. By TPP-DLW and one-photon lithography, a 3D fluorescent design can be concealed inside a polymeric microstructure that is swiftly fabricated using a photoresist. An example of a 3D crypto-image is shown to illustrate the technique.

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Reaction Mechanisms and In Situ Process Diagnostics

Cited by 9 publications

References 25 publications

Processes of Direct Laser Writing 3D Nano-Lithography

Processes of Direct Laser Writing 3D Nano-Lithography

Characterization of two-photon-polymerization lithography structures via Raman spectroscopy and nanoindentation

Three-Dimensional Photoluminescent Crypto-Images Doped with (CdSe)ZnS Quantum Dots by One-Photon and Two-Photon Polymerization

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