Vitrimers brought new properties in thermosets by allowing their reshaping, self-healing, reprocessing, and network rearrangement without changing structural integrity. In this study, epoxidized castor oil (ECO) was successfully used for the straightforward synthesis of a bio-based solvent-free vitrimer. The synthesis was based on a UV-curing process, which proceeded at low temperatures in the absence of any solvents, and within a short time. Real time Fourier-transformed infrared spectroscopy and photo-DSC were exploited to monitor the cationic photocurable process. The UV-cured polymer networks were able to efficiently undergo thermo-activated bond exchange reactions due to the presence of dibutyl phosphate as a transesterification catalyst. Mechanical properties, thermal resistance, glass transition temperature, and stress relaxation were investigated as a function of the amount of transesterification catalyst. Mechanical properties were determined by both DMTA and tensile tests. Glass transition temperature (T_g) was evaluated by DMTA. Thermal stability was assessed by thermogravimetric analysis, whilst vitrimeric properties were studied by stress relaxation experiments. Overall, the ECO-based vitrimer showed high thermal resistance (up to 200 °C) and good mechanical properties (elastic modulus of about 10 MPa) and can therefore be considered as a promising starting point for obtaining more sustainable vitrimers.

In this study, a bio-based acrylate resin derived from soybean oil was used in combination with a reactive diluent, isobornyl acrylate, to synthetize a composite scaffold reinforced with bioactive glass particles. The formulation contained acrylated epoxidized soybean oil (AESO), isobornyl acrylate (IBOA), a photo-initiator (Irgacure 819) and a bioactive glass particle. The resin showed high reactivity towards radical photopolymerisation, and the presence of the bioactive glass did not significantly affect the photocuring process. The 3D-printed samples showed different properties from the mould-polymerised samples. The glass transition temperature T_g showed an increase of 3D samples with increasing bioactive glass content, attributed to the layer-by-layer curing process that resulted in improved interaction between the bioactive glass and the polymer matrix. Scanning electron microscope analysis revealed an optimal distribution on bioactive glass within the samples. Compression tests indicated that the 3D-printed sample exhibited higher modulus compared to mould-synthetized samples, proving the enhanced mechanical behaviour of 3D-printed scaffolds. The cytocompatibility and biocompatibility of the samples were evaluated using human bone marrow mesenchymal stem cells (bMSCs). The metabolic activity and attachment of cells on the samples’ surfaces were analysed, and the results demonstrated higher metabolic activity and increased cell attachment on the surfaces containing higher bioactive glass content. The viability of the cells was further confirmed through live/dead staining and reseeding experiments. Overall, this study presents a novel approach for fabricating bioactive glass reinforced scaffolds using 3D printing technology, offering potential applications in tissue engineering.

The paradigm shift from traditional petroleum‐based non‐recyclable thermosets to biobased repeatedly recyclable materials is required to move toward circular bioeconomy. Here, two mechanically and chemically recyclable extended vanillin‐derived epoxy thermosets are successfully fabricated by introduction of Schiff‐base/imine covalent dynamic bonds. Thermoset 1 (T1) is based on linear monomer 1 (M1) with two alcohol end groups and one imine bond, while thermoset 2 (T2) is based on branched monomer 2 (M2) with three alcohol end‐groups and three imine‐groups. Thermosets are obtained by reaction of monomer 1 (M1) and monomer 2 (M2) with trimethylolpropane triglycidyl ether. The structure of the monomers and thermosets is confirmed by nuclear magnetic resonance and Fourier transform infrared spectroscopic techniques. Both thermosets exhibit good thermal and mechanical properties and they are stable in common organic solvents. Furthermore, they can be thermally reprocessed through compression molding with good recovery of the mechanical properties. Last but not least, the fabricated thermosets can be rapidly and completely chemically recycled to water‐soluble aldehydes and amines by imine hydrolysis at room temperature in 0.1 m HCl solution. This is promising for development of future materials with multiple circularity by different routes.

In this study, we present novel, vitrimeric and biobased scaffolds that are designed for hard tissue applications, composed of acrylated, epoxidized soybean oil (AESO) and reinforced with bioactive glass that is Tellurium doped (BG-Te) and BG-Te silanized, to tune the mechanical and antibacterial properties. The manufacture’s method consisted of a DLP 3D-printing method, enabling precise resolution and the possibility to manufacture a hollow and complex structure. The resin formulation was optimized with a biobased, reactive diluent to adjust the viscosity for an optimal 3D-printing process. The in vitro biological evaluation of the 3D-printed scaffolds, combined with BG-Te and BG-Te-Sil, showed that the sample’s surfaces remained safe for hBMSCs’ attachment and proliferation. The number of S. aureus that adhered to the BG-Te was 87% and 54% lower than on the pristine (control) and BG-Te-Sil, respectively, with the eradication of microbiofilm aggregates. This work highlights the effect of the vitrimeric polymer matrix and doped, bioactive glass in manufacturing biocompatible, biobased, and antibacterial scaffold used in hard tissue application.

The photopolymerization process in 3D printing is considered greener once it involves a fast reaction and low energy consumption. Various reactions for photopolymerization can be used nowadays, but a special one is the thiol-ene “click” reaction that occurs in equimolar concentrations of thiol and alkene groups. In this sense, solvent-free photopolymerizable formulations were prepared to contain non-modified castor oil, Trimethylolpropane tris(3-mercapto propionate), and cellulosic fillers from hemp, tagua, and walnut. All formulations presented conversions higher than 70% and fast polymerization rates. Moreover, the filled formulations presented excellent curing depths in fewer seconds of light exposition, an important factor for their applicability in 3D printing. Furthermore, the hemp filler formulation presented the highest crosslinking density as determined by the DMTA, and was selected for printing two complex structures (pyramid and honeycomb shape). The rheology analysis showed that the formulations had adequate viscosities for the printer. Lastly, all polymers presented at least 97% bio-based contents, with gel contents superior to 96%.