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Selection of conventional photoinitiators to produce biocompatible UV epoxidized soybean oil resin mixtures for 3D printing technology
1 , 1 , 2, 3 , 4, 5 , * 2, 6
1  DEQ, ISEL-IPL, Rua Conselheiro Emídio Navarro 1, 1959-007 Lisboa, Portugal.
2  DEQ, ISEL-IPL, Rua Conselheiro Emídio Navarro 1, 1959-007 Lisboa, Portugal;
3  GeoBioTec, FCT-UNL, Monte de Caparica, 2829-516 Caparica, Portugal;
4  IDMEC, IST-UL, Avenida Rovisco Pais, 1049-001 Lisboa, Portugal;
5  CIMOSM, ISEL-IPL, Rua Conselheiro Emídio Navarro, 1, 1959-007 Lisboa, Portugal;
6  CQE, IMS, IST-UL, Avenida Rovisco Pais, 1049-001 Lisboa, Portugal.
Academic Editor: Nunzio Cennamo


The use of natural-based resins as matrices for 3D printing is currently an expanding area with a considerable potential to explore. These materials, in addition to presenting high biocompatibility, come from renewable natural resources, making them very attractive in terms of cost and environmental needs. In the production of objects by photopolymerization, natural-based resins can be used with photoinitiators, making them amenable to UV-curing. Thus, the choice of natural resins, photoinitiators and light sources, which allow proposing new formulations, with the biocompatibility properties of the natural material, and which can compete with those available on the market, justify research in this area. Whitin this context, five conventional photoinitiators namely, benzophenone, 2,2-dimethoxy-2-phenylacetophenone, ethylphenyl (2,4,6-trimetylbenzoyl) phosphinate, 2-chlorothioxannthen-9-one and 2-isopropylthioxanthone were tested and evaluated to promote de UV-curing of a natural resin derived from epoxidized soybean oil. Different mixtures were prepared, with 1-0.01% of photoinitiators (w/w, initial resin basis) and operational parameters such as time and wave-length source, were tested. Cured mixtures were evaluated concerning physicochemical structure, mechanical and biological properties. Results showed that, of the five photoinitiators studied, the most suitable to produce epoxidized soybean oil resin mixtures for 3D printing was ethylphenyl (2,4,6-trimetylbenzoyl) phosphinate. With its use, even in reduced amounts 0.01% (w/w), it was possible to produce transparent films and print pieces by stereolithography, with greater thickness, than those displayed by similar pieces prepared from mixtures of the same resin with other photoinitiators. The mechanical properties were similar to those obtained for the pieces produced with a commercial resin, which was used as reference, and no antibacterial activity was evidenced against Escherichia coli and Staphylococcus aureus by these new materials.

Keywords: 3D printing; biocompatible mixtures; soybean resin; photoinitiators; UV-curing.