Additives for Ambient 3D Printing with Visible Light

10.26434/chemrxiv.14390828 ◽

2021 ◽

Author(s):

Dowon Ahn ◽

Lynn Stevens ◽

Kevin Zhou ◽

Zachariah Page

Keyword(s):

3D Printing ◽

Visible Light ◽

Reaction Times ◽

High Energy ◽

Energy Methods ◽

Mechanical Responses ◽

Violet Light ◽

Acrylic Resins ◽

Printing Processes ◽

Made In

With 3D printing we desire to be “limited only by our imagination”, and although remarkable advancements have been made in recent years the scope of printable materials remains narrow compared to other forms of manufacturing. Light-driven polymerization methods for 3D printing are particularly attractive due to unparalleled speed and resolution, yet the reliance on high energy UV/violet light in contemporary processes limits the number of compatible materials due to pervasive absorption, scattering, and degradation at these short wavelengths. Such issues can be addressed with visible light photopolymerizations. However, these lower-energy methods often suffer from slow reaction times and sensitivity to oxygen, precluding their utility in 3D printing processes that require rapid hardening (curing) to maximize build speed and resolution. Herein, multifunctional thiols are identified as simple additives to enable rapid high resolution visible light 3D printing under ambient (atmospheric O2) conditions that rival modern UV/violet-based technology. The present process is universal, providing access to commercially relevant acrylic resins with a range of disparate mechanical responses from strong and stiff to soft and extensible. Pushing forward, the insight presented within this study will inform the development of next generation 3D printing materials, such as multicomponent hydrogels and composites.

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Rapid High Resolution Visible Light 3D Printing

10.26434/chemrxiv.12644126.v1 ◽

2020 ◽

Author(s):

Dowon Ahn ◽

Lynn Stevens ◽

Kevin Zhou ◽

Zachariah Page

Keyword(s):

High Resolution ◽

3D Printing ◽

Visible Light ◽

Mechanical Performance ◽

Screening Method ◽

Reaction Times ◽

High Energy ◽

Solid Objects ◽

Soft Objects ◽

Visible Wavelengths

Light-driven 3D printing to convert liquid resins into solid objects (i.e., photocuring) has traditionally been dominated by engineering disciplines, yielding the fastest build speeds and highest resolution of any additive manufacturing process. However, the reliance on high energy UV/violet light derived from decades of photolithography research, limits the materials scope due to degradation and attenuation (e.g., absorption and/or scattering). Chemical innovation to shift the spectrum into more mild and tunable visible wavelengths promises to improve compatibility and expand the repertoire of accessible objects, including those containing biological compounds and multi-material structures. Photochemistry at these longer wavelengths currently suffers from slow reaction times precluding its utility. Herein, novel panchromatic photopolymer resins were developed and applied for the first time to realize rapid high resolution visible light 3D printing. The combination of electron deficient iodonium and rich borate co-initiators were critical to overcoming the speed-limited photocuring with visible light. Furthermore, azo-dyes were identified as vital resin components to confine curing to irradiation zones, improving spatial resolution. A unique screening method was used to streamline optimization (e.g., exposure time and azo-dye loading) and correlate resin composition to resolution, cure rate, and mechanical performance. Ultimately, a versatile and general visible light-based printing method was shown to afford 1) stiff and soft objects with feature sizes < 100 μm, 2) build speeds up to 45 mm/h, and 3) mechanical isotropy, rivaling modern UV-based 3D printing technology and providing a foundation from which bio- and composite-printing can emerge.

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Rapid High Resolution Visible Light 3D Printing

10.26434/chemrxiv.12644126 ◽

2020 ◽

Author(s):

Dowon Ahn ◽

Lynn Stevens ◽

Kevin Zhou ◽

Zachariah Page

Keyword(s):

High Resolution ◽

3D Printing ◽

Visible Light ◽

Mechanical Performance ◽

Screening Method ◽

Reaction Times ◽

High Energy ◽

Solid Objects ◽

Soft Objects ◽

Visible Wavelengths

Light-driven 3D printing to convert liquid resins into solid objects (i.e., photocuring) has traditionally been dominated by engineering disciplines, yielding the fastest build speeds and highest resolution of any additive manufacturing process. However, the reliance on high energy UV/violet light derived from decades of photolithography research, limits the materials scope due to degradation and attenuation (e.g., absorption and/or scattering). Chemical innovation to shift the spectrum into more mild and tunable visible wavelengths promises to improve compatibility and expand the repertoire of accessible objects, including those containing biological compounds and multi-material structures. Photochemistry at these longer wavelengths currently suffers from slow reaction times precluding its utility. Herein, novel panchromatic photopolymer resins were developed and applied for the first time to realize rapid high resolution visible light 3D printing. The combination of electron deficient iodonium and rich borate co-initiators were critical to overcoming the speed-limited photocuring with visible light. Furthermore, azo-dyes were identified as vital resin components to confine curing to irradiation zones, improving spatial resolution. A unique screening method was used to streamline optimization (e.g., exposure time and azo-dye loading) and correlate resin composition to resolution, cure rate, and mechanical performance. Ultimately, a versatile and general visible light-based printing method was shown to afford 1) stiff and soft objects with feature sizes < 100 μm, 2) build speeds up to 45 mm/h, and 3) mechanical isotropy, rivaling modern UV-based 3D printing technology and providing a foundation from which bio- and composite-printing can emerge.

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Rapid Crystallization and Kinetic Freezing of Site-Disorder in the Lithium Superionic Argyrodite Li6PS5Br

10.26434/chemrxiv.9794588 ◽

2019 ◽

Author(s):

Ajay Gautam ◽

Marcel Sadowski ◽

Nils Prinz ◽

Henrik Eickhoff ◽

Nicolo Minafra ◽

...

Keyword(s):

Elevated Temperatures ◽

Synthesis Method ◽

Reaction Times ◽

Ionic Conductivities ◽

Ionic Transport ◽

High Energy ◽

Superionic Conductors ◽

Rapid Crystallization ◽

Site Disorder ◽

Fast Cooling

Lithium argyrodite superionic conductors are currently being investigated as solid electrolytes for all-solid-state batteries. Recently, in the lithium argyrodite Li6PS5X (X = Cl, Br, I), a site-disorder between the anionsS2–and X–has been observed, which strongly affects the ionic transport and appears to be a function of the halide present. In this work, we show how such disorder in Li6PS5Br can be engineered viathe synthesis method. By comparing fast cooling (i.e. quenching) to more slowly cooled samples, we find that anion site-disorder is higher at elevated temperatures, and that fast cooling can be used to kinetically trap the desired disorder, leading to higher ionic conductivities as shown by impedance spectroscopy in combination with ab-initiomolecular dynamics. Furthermore, we observe that after milling, a crystalline lithium argyrodite can be obtained within one minute of heat treatment. This rapid crystallization highlights the reactive nature of mechanical milling and shows that long reaction times with high energy consumption are not needed in this class of materials. The fact that site-disorder induced viaquenching is beneficial for ionic transport provides an additional approach for the optimization and design of lithium superionic conductors.

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Influence of Constructive and Technological Parameters at Generated Spiral Parts with DLP 3D Printing Process

Materiale Plastice ◽

10.37358/mp.19.4.5269 ◽

2019 ◽

Vol 56 (4) ◽

pp. 801-811

Author(s):

Mircea Dorin Vasilescu

Keyword(s):

3D Printing ◽

Great Influence ◽

Polymerization Process ◽

Generation Process ◽

Technological Parameters ◽

Printing Process ◽

The Third ◽

Solid Models ◽

Specific Factors ◽

Printing Processes

This work are made for determine the possibility of generating the specific parts of a threaded assembly. If aspects of CAD generating specific elements was analysed over time in several works, the technological aspects of making components by printing processes 3D through optical polymerization process is less studied. Generating the threaded appeared as a necessity for the reconditioning technology or made components of the processing machines. To determine the technological aspects of 3D printing are arranged to achieve specific factors of the technological process, but also from the specific elements of a trapezoidal thread or spiral for translate granular material in supply process are determined experimentally. In the first part analyses the constructive generation process of a spiral element. In the second part are identified the specific aspects that can generation influence on the process of realization by 3D DLP printing of the two studied elements. The third part is affected to printing and determining the dimensions of the analysed components. We will determine the specific value that can influence the process of making them in rapport with printing process. The last part is affected by the conclusions. It can be noticed that both the orientation and the precision of generating solid models have a great influence on the made parts.

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Efficient 3D printing via photooxidation of ketocoumarin based photopolymerization

Nature Communications ◽

10.1038/s41467-021-23170-4 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Xiaoyu Zhao ◽

Ye Zhao ◽

Ming-De Li ◽

Zhong’an Li ◽

Haiyan Peng ◽

...

Keyword(s):

Additive Manufacturing ◽

3D Printing ◽

Visible Light ◽

Light Exposure ◽

Three Dimensional ◽

3D Printer ◽

Light Penetration ◽

Viable Solution

AbstractPhotopolymerization-based three-dimensional (3D) printing can enable customized manufacturing that is difficult to achieve through other traditional means. Nevertheless, it remains challenging to achieve efficient 3D printing due to the compromise between print speed and resolution. Herein, we report an efficient 3D printing approach based on the photooxidation of ketocoumarin that functions as the photosensitizer during photopolymerization, which can simultaneously deliver high print speed (5.1 cm h−1) and high print resolution (23 μm) on a common 3D printer. Mechanistically, the initiating radical and deethylated ketocoumarin are both generated upon visible light exposure, with the former giving rise to rapid photopolymerization and high print speed while the latter ensuring high print resolution by confining the light penetration. By comparison, the printed feature is hard to identify when the ketocoumarin encounters photoreduction due to the increased lateral photopolymerization. The proposed approach here provides a viable solution towards efficient additive manufacturing by controlling the photoreaction of photosensitizers during photopolymerization.

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