Self-focusing 3D lithography with varying refractive index polyethylene glycol diacrylate

Takahashi, Hidetoshi; Kan, Tetsuo; Lee, Gayeong; Dönmez, Nilsu; Kim, Jieun; Park, Jihoon; Kim, Dong-Wook; Heo, Yun Jung

doi:10.35848/1882-0786/ab9ba3

Cited by 13 publications

(15 citation statements)

References 24 publications

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“…Previous experimental studies , have shown that the refractive index of a UV-curable resin increases during polymerization. The influence of the varying resin refractive indices on the spatial and temporal DoC distributions of UV-curable systems was investigated using the P-FDTD framework.…”

Section: Resultsmentioning

confidence: 97%

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Combining FDTD and Curing Kinetic Equations to Model the Degree of Conversion Evolution of UV-Curable Systems

Xie

Basu

DeMeter

2021

Ind. Eng. Chem. Res.

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The degree of conversion (DoC) is significantly linked with many material properties of a UV-cured resin. The current curing kinetic models provide insight into how DoC evolves with depth for a pure resin subject to plane wave, light propagation. However, they do not accurately describe how DoC evolves within UV-curable composites or systems in which multidirectional ray propagation and interference are in play. This paper describes a simulation framework for predicting the spatial and temporal eand the propagation is alovolution of DoC within a UV-curable composite. The framework uses Maxwell's laws of electromagnetic theory and a series of finite-difference timedomain (FDTD) simulations to predict light intensity distribution at different reaction time steps. It also uses curing kinetic models and optical property models to predict DoC and optical properties within a volume. The framework was applied to simulate the photoinduced, free-radical polymerization of poly(ethylene glycol) diacrylate/2,2-dimethoxy-2-phenyl acetophenone (PEGDA/ DMPA)-based composites. It was used to study the influence of the resin refractive index, the filler refractive index, and the filler particle size on the spatial and temporal evolution of DoC. The predictions of DoC evolution were in agreement with both theoretical and experimental results published in the research literature. The simulations also revealed that (1) the change of the resin refractive index during polymerization has a significant impact on both light propagation and DoC within a UV-curable composite, (2) smaller fillers scatter more light than larger fillers, and (3) larger refractive index mismatch between the resin and filler leads to more light scattering and greater light attenuation. In turn, this increases the polymerization rate at shallow depths but decreases it at greater depths.

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Section: Resultsmentioning

confidence: 97%

“…This value is the refractive index of uncured PEGDA. However, it is essential to point out that the refractive index of PEGDA increases during polymerization . Such effects will be discussed in the later sections.…”

Section: Resultsmentioning

confidence: 99%

Combining FDTD and Curing Kinetic Equations to Model the Degree of Conversion Evolution of UV-Curable Systems

Xie

Basu

DeMeter

2021

Ind. Eng. Chem. Res.

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“…1b . 24 Fig. 1c shows a picture of cone-shaped MNs, fabricated on a flexible PET film, using photopolymerization.…”

Section: Resultsmentioning

confidence: 99%

“…Takahashi et al reported the self-focusing effect in fabricating MNs by the reflection on the interface between the solidified and liquid prepolymer, and UV light rays diverged after reaching the critical point and converged again to form gourd-shaped MNs. 24 …”

Section: Resultsmentioning

confidence: 99%

“…Takahashi et al reported the self-focusing effect in fabricating MNs by the reection on the interface between the solidied and liquid prepolymer, and UV light rays diverged aer reaching the critical point and converged again to form gourd-shaped MNs. 24 Effects of molar extinction coefficients of PIs PIs are very important for FRPs. A PI has a specic molar extinction coefficient value at a particular wavelength, which is one of the major factors affecting light absorption.…”

Section: Effect Of Prepolymer Molecular Weightmentioning

confidence: 99%

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Investigation on photopolymerization of PEGDA to fabricate high-aspect-ratio microneedles

et al. 2022

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Direct Laser Writing of Silica Nanoparticle Nanocomposites: Probing Mechanical Reinforcement and Understanding Structural Color from Design Parameters

Augustine,

Qian,

Faraone

et al. 2024

Small

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Nanocomposite materials have been thoroughly exploited in additive manufacturing, as a means to alter physical, chemical, and optical properties of resulting structures. Herein, nanocomposite materials suitable for direct laser writing (DLW) by two‐photon polymerization are presented. These materials, comprising silica nanoparticles, bring significant added value to the technology through physical reinforcement and controllable photonic properties. Incorporation into acrylate photoresists, via a one‐step fabrication process, enables the formation of complex structures with large overhangs. The inclusion of 150 nm silica nanoparticles in DLW photoresists at high concentrations, allows for the fabrication of composite microstructures that show reflected color, a product of the relative contributions from the quasi‐ordering and random scattering. Using common DLW design parameters, such as slicing distance and structure dimension, a wide gamut of structural color, in solution, using a set concentration of nanoparticles is demonstrated. Numerical modeling is employed to predict the reflected wavelength of the pixel arrays, across the visible spectrum, and this information is used to encode reflected colors into different pixel arrays.

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Self-focusing 3D lithography with varying refractive index polyethylene glycol diacrylate

Cited by 13 publications

References 24 publications

Combining FDTD and Curing Kinetic Equations to Model the Degree of Conversion Evolution of UV-Curable Systems

Combining FDTD and Curing Kinetic Equations to Model the Degree of Conversion Evolution of UV-Curable Systems

Investigation on photopolymerization of PEGDA to fabricate high-aspect-ratio microneedles

Direct Laser Writing of Silica Nanoparticle Nanocomposites: Probing Mechanical Reinforcement and Understanding Structural Color from Design Parameters

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