Page 90 - MSAM-3-2

Materials Science in Additive Manufacturing Sustainable resin for coral restoration

the cells’ nuclei. The imaging of the stained cells was CCP resin, employing a table-top stereolithography printer
40
conducted using the EVOS M7000 Imaging System, and (LCD-based, ELEGOO Mars 3), as depicted in Figure 5.
a confocal microscope (LSM 710 Laser Scanning Confocal The UV light source utilized had a wavelength of 405 nm,
Microscope, Germany) was used for higher resolution and facilitating the printing of the coral plugs in good resolution.
Z-stack images. 41
3.1. Effect of adding diluent to resin formulation
2.2.7. Microfragmentation on coral plugs The impact of the diluent is evident in Figure 6, where the
To evaluate the suitability of the materials for coral coral plug on the right side, printed without the diluent,
restoration, healthy coral fragments retrieved from the appears distorted. In contrast, the plug on the left side,
Red Sea were carefully chosen and fixed onto three printed printed with the addition of diluent, displays improved
AESO and modified CCP resin coral plugs. Serving as structural integrity. Incorporating a diluent, also known as
comparative controls, three ceramic coral plugs (Reefing monomer or thinner, into the resin offers several benefits
Art Ceramic Coral Frag Plugs, USA), commonly utilized in for 3D printing: Diluents effectively reduce the resin’s
the coral restoration field, were included in the experiment. viscosity, making it less thick and facilitating smoother
The coral fragments, ranging approximately 1.5–2.5 cm flow. During the printing process, as each layer is formed,
43
in size, were carefully excised from the same colony to the building platform is lifted, requiring the resin to flow
maintain uniformity (Acropora species). To securely beneath it to ensure adequate resin for the subsequent
42
44
attach the coral fragments to the plugs, a small quantity layer. Moreover, the acrylate diluent reinforces the
of coral glue (Aqua Medic Coral Construct, Switzerland) mechanical strength of the cured AESO resin by promoting
was applied at the center of the coral plugs. Subsequently, a higher level of crosslinking. The AESO molecules, being
the coral plugs with the attached fragments were affixed to relatively bulky, face challenges in initiating polymerization
a mesh and placed in an outdoor seawater tank for further through their double bonds. However, introducing a
observation and growth monitoring before out-planting, smaller monomer facilitates a more efficient crosslinking
as depicted in Figure 4. The seawater tank was maintained process, leading to improved mechanical properties in
45
at specific environmental conditions, with a pH of 8.2, the final printed object. In addition, the acrylate diluent
temperature of 25.7°C, and salinity level of 4.1 g/100 g. enhances the solubility of the photoinitiator within the
The coral plugs within the tank were carefully monitored resin. For instance, Irgacure 819 demonstrates relatively
every week to evaluate the coral growth and development. good solubility in 1,6-hexanediol diacrylate (HDDA) at
46
Regular deep tank cleaning was conducted to mitigate algae 10% w/v. In terms of cost evaluation, diluting the resin
overgrowth on coral, thereby maintaining an environment with a diluent reduces the consumption of the original,
conducive to the growth of the coral fragments. more expensive resin. Reducing material usage helps to
minimize waste and lowers production costs, making the
3. Results and discussion 3D printing process more economically viable.

In this section, we present the results of successfully However, excessive dilution can compromise the
printing the coral plugs using the novel AESO and modified mechanical properties and final quality of the printed

Figure 4. Schematic illustration of coral microfragmentation on coral plug.

Volume 3 Issue 2 (2024) 6 doi: 10.36922/msam.3125