Rapid 3D printing with visible light

Date:
September 16, 2020
Source:
American Chemical Society
Summary:
3D printing has driven innovations in fields ranging from art
to aerospace to medicine. However, the high-energy ultraviolet
(UV) light used in most 3D printers to cure liquid resins into
solid objects limits the technique's applications. Visible-light
curing, which would be more appropriate for some uses, such as
tissue engineering and soft robotics, is slow. Now, researchers
have developed photopolymer resins that boost the speed of
visible-light curing.



FULL STORY ==========================================================================
3D printing has driven innovations in fields ranging from art to
aerospace to medicine. However, the high-energy ultraviolet (UV) light
used in most 3D printers to cure liquid resins into solid objects limits
the technique's applications. Visible-light curing, which would be more appropriate for some uses, such as tissue engineering and soft robotics,
is slow. Now, researchers reporting in ACS Central Science have developed photopolymer resins that boost the speed of visible-light curing.


==========================================================================
With the help of computer-aided design, 3D-printed objects are made by
the successive layering of a material into a 3D shape, with each layer solidified or "cured" using UV light. Being able to use visible light
for curing would have advantages, including reduced cost, improved biocompatibility, greater depth of light penetration and reduced light scattering. These attributes could open up new applications for 3D
printing, such as making opaque composites, multi-material structures
or hydrogels containing live cells. However, because visible light is
lower in energy than UV, visible-light curing is currently too slow
to be practical. Zachariah Page and colleagues wanted to find a way to
speed up the process.

The researchers developed violet-, blue-, green- and red-colored resins
that contained a monomer, a photoredox catalyst (PRC), two co-initiators
and an opaquing agent. When the PRC absorbed visible light from LEDs,
it catalyzed the transfer of electrons between the co-initiators,
which generated radicals that caused the monomer to polymerize. The
opaquing agent helped confine curing to the areas struck by light, which improved spatial resolution. The optimized mix of components allowed
the researchers to print stiff and soft objects with small features
(less than 100 ?m), mechanical uniformity and build speeds up to 1.8
inches per hour. Although the best build speed is still less than half
that of the fastest rate obtained using UV light, it could be further
improved by increasing the light intensity or adding other components
to the resin, the researchers say.


========================================================================== Story Source: Materials provided by American_Chemical_Society. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Dowon Ahn, Lynn M. Stevens, Kevin Zhou, Zachariah A. Page. Rapid
High-
Resolution Visible Light 3D Printing. ACS Central Science, 2020;
DOI: 10.1021/acscentsci.0c00929 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200916113424.htm

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