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Materials Science in Additive Manufacturing Sustainable resin for coral restoration

many coral restoration projects concentrate on supporting to create 3D-printed ceramic tiles, effectively mimicking
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and facilitating the growth of coral skeletons. the morphologies of natural coral structures. In recent
The rapid development of 3D printing technology (also years, biodegradable substrates have gained prominence
known as additive manufacturing) in recent years has in many applications. Biopolymer-based materials,
offered a promising tool for coral restoration purposes. 3D specifically designed to degrade over time, can provide
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temporary support for coral growth while promoting
printing can produce 3D objects by layering materials natural integration with the surrounding environment.
such as plastic, ceramic, or metal according to the digital
design. Artificial reefs that mirror the complexity and One of the most common examples is acrylated
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morphology of the original coral reefs have been made epoxidized soybean oil (AESO). AESO is a form of acrylate
using this technology, offering coral polyps a substrate to polymer that originates from the chemical transformation
attach and flourish. of soybean oil. This process involves the initial reaction of
soybean oil with hydrogen peroxide to produce epoxidized
3D printing enables exact control over the size and soybean oil (ESO). Following this, ESO is further processed
structure of the artificial reef, allowing it to be customized through a reaction with acrylic acid or methacrylic acid,
to the unique requirements of various coral species and forming AESO. 20,21 The resulting AESO has a high degree
marine environments with less labor. However, some of functionality due to the high double bond concentration
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issues still need to be resolved, such as ensuring the from the acrylate group, allowing it to be used as a resin for
materials/resin used for 3D printing are secure for marine 3D printing 22-24 and other applications. AESO-based resin
life in the long term, as well as optimizing the structural affords eco-friendly and sustainable ways to construct
design. In addition, the cost of the materials and the biomaterials. The molecular structure of AESO consists
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scalability of the prints are also topics of concern. Despite of natural fatty acids, which have negligible cytotoxicity.
the challenges, researchers have been actively exploring
various 3D printing techniques for coral restoration Previously, our group at the Laboratory for
purposes and have already made some significant progress. Nanomedicine developed a specialized ink called calcium
carbonate-photoinitiated ink (CCP) by mixing 70%
One of the examples is the “Coral Carbonate” project, commercially available photocurable resin (Anycubic
led by the objects and ideograms design workshop. They Plant-Based UV Resin, China) with 30% calcium carbonate
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created a calcium carbonate-based coral skeleton using to fabricate coral skeletons using extrusion-based 3D
binder jetting technique, with the powder ground from printing. In this work, the primary objective is to optimize
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natural coral rubble. Paste-based extrusion is another the CCP and modify the current formulation to develop a
popular technique for coral restoration. Examples of such more sustainable resin formulation for fabricating 3D coral
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applications include 3DPARE modules and the Rexcor plugs using the DLP printing technique. In addition, we
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reef by XtreeE. 15 aim to evaluate the biocompatibility of the modified CCP
Vat polymerization is a widely used 3D printing technique with coral fragments and assess its cytotoxicity to cells.
that falls under the category of photopolymerization In the subsequent chapter, the resin will be referred to as
processes. One of the most common vat polymerization “modified CCP.”
methods is digital light processing (DLP), a technique In addition, various material characterizations were
that utilizes a digital light projector to selectively cure conducted to test the scaffold’s composition, morphology,
photopolymer resins. In general, DLP offers faster printer glass transition temperature, and wettability. This study
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speed and different material selection compared to other advances the coral restoration effort using sustainable
printing techniques. To the best of our knowledge, coral plant-based soybean oils and vat photopolymerization
restoration projects using the vat polymerization technique method. With continued research and innovation, we hope
are rarely reported thus far. to see more practical and cost-effective solutions soon that
can help protect and preserve coral reefs for generations
One of the key challenges in 3D printing of coral
skeletons is choosing the appropriate materials/resin for to come.
printing. Further investigations on many conventional 3D 2. Experimental methods
printing materials, such as thermoplastics and metals, are
warranted due to their potential to leach harmful chemicals 2.1. Resin preparation and coral plugs fabrication
or micro-plastics and their limited degradability over time. The objective of this paper is to print a relatively simple
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As a result, a range of biocompatible and environmentally structure, namely, coral plugs for the microfragmentation
friendly materials have been explored such as limestone. experiment. These plugs are widely used in the realm of coral
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In addition, ceramic terracotta materials have been utilized restoration. Figure 1 shows an example of commercially
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Volume 3 Issue 2 (2024) 2 doi: 10.36922/msam.3125