Synthesis and characterization of bio-based polymers for innovative additive manufacturing applications via stereolithography 3D printing

This thesis focused on the study and development of bio-based and biocompatible photosensitive resin for stereolithography 3D printing. One of the seven additive manufacturing technologies, vat photopolymerization, utilizes a combination of liquid photosensitive polymers with a photoinitiator and a UV emitter to fabricate objects. The main advantage of this method is that it allows the creation of highly detailed objects. Indeed, this is the main reason why vat photopolymerization is interesting for biomedical applications, whereby combining it with other imaging techniques, it is possible to create patient-made prothesis and implants. Unfortunately, most resins used nowadays are derived from petroleum, limiting their application. Different types of materials were proposed to expand the variety of bio-resins. Among all, vegetable oils and plant-based resins demonstrated some promising properties. They are available worldwide and have relatively low production costs. Moreover, they can be easily functionalized to be suitable for photopolymerization. Soybean oil being a good example. Its functionalization is already used for UV coating, but its full potential in 3D printing is yet to be explored. In this research study, the utilization of functionalized soybean oil, more precisely, acrylated epoxidized soybean oil (AESO), for 3D-printing was investigated. Here, AESO was tested for different application: from improving the biobased content of commercial a resin, to the synthesis and optimization of complete biobased and biocompatible resins. For the first study, increasing concentrations of neat AESO were combined with Peopoly moai standard clear resin, where its influence on the resin performance was tested using different characterization techniques. Tensile test results were also compared with data from other standards of commercial resins to see how it would scale. The doping of petroleum-based resins with biobased resins is interesting since it is a simple method to increase the bio-renewable content of such materials. However, the main objective is the transitioning from petroleum-based to complete bio resins, thus for that, in the subsequent study, AESO was combined with another plant-based material to develop a biobased resin. The mechanical and curing properties of this new resin were again compared with various standard resins to verify its performance. Furthermore, other characterization analyzes were done to better understand its photopolymerization reaction and final application. Based on the information obtained from developing a biobased resin, AESO was used for creating a biocompatible resin. For that, it was combined with a known biocompatible material, poly(ethylene) diacrylate, and different physical and chemical properties were studied. Furthermore, the mixture which demonstrated the best performance was used in a following study that had the objective to add nanoparticles to improve its mechanical properties. The fillers used were micro- and nano- crystalline cellulose, a natural material that has already shown remarkable properties at low dosages. The studies presented in this work are only the beginning. Further research needs to be carried out to test the performance of the biocompatible resins developed in cell cultures. Future perspectives can also consist of the evaluation of different vegetable oils, or the usage of non-food related materials (ex: algae) to develop these new bio-resins. Additionally, other types of particles can be explored as well to add new properties, such as flame retardancy, conductivity, memory shape, and others.