Polymer-Derived Biosilicate®-like Glass-Ceramics: Engineering of Formulations and Additive Manufacturing of Three-Dimensional Scaffolds

Abstract

Silicone resins, filled with phosphates and other oxide fillers, yield upon firing in air at 1100 °C, a product resembling Biosilicate® glass-ceramics, one of the most promising systems for tissue engineering applications. The process requires no preliminary synthesis of parent glass, and the polymer route enables the application of direct ink writing (DIW) of silicone-based mixtures, for the manufacturing of reticulated scaffolds at room temperature. The thermal treatment is later applied for the conversion into ceramic scaffolds. The present paper further elucidates the flexibility of the approach. Changes in the reference silicone and firing atmosphere (from air to nitrogen) were studied to obtain functional composite biomaterials featuring a carbon phase embedded in a Biosilicate®-like matrix. The microstructure was further modified either through a controlled gas release at a low temperature, or by the revision of the adopted additive manufacturing technology (from DIW to digital light processing).

Influence of the Pyrolysis Temperature and TiO2-Incorporation on the Properties of SiOC/SiC Composites for Efficient Wastewater Treatment Applications

“…Additionally, the mixture of these polysiloxanes shows other advantages: because the decomposition of phenyl groups starts at lower temperatures (420-500 • C) than that of methyl groups (T > 600 • C), the use of H44 results in higher BET surface areas and lower hydrophobicity than MK when pyrolyzed at lower temperatures (500-600 • C) [18,44]. On the other hand, MK offers a higher ceramic yield (84 wt%) than H44 (72 wt%) under N 2 at 1000 • C [45]. Complementary amounts of SiC (6.5 µm) and TiO 2 (21 nm) were used as fillers in order to prevent the characteristic shrinkage of polysiloxanes-based material during the pyrolysis process, to increase mechanical stability, and to evaluate the effect of these micro-and nanofillers on the morphology, pore size, and surface characteristics of PDC membranes.…”

“…The adsorption and the photocatalytic performances of the produced samples were assessed in a series of tests using methylene blue (MB) as a tracer dye and a UV light source. The initial results (Figure S3a) showed a significant adsorption of MB by the produced PDC material, and that the commonly used period of 2 h for adsorption in the dark [40,45,46] was not sufficient to reach equilibrium. Therefore, performing irradiation experiments after a short adsorption time in the dark would lead to misleading photocatalytic degradation capacities.…”

“…The advantage of the coating procedure is that TiO 2 is more readily accessible to light irradiation on the surface of the material than it is when entrapped in its matrix, while the disadvantage is the necessity of a secondary thermal process, which can represent an increase in the production cost. The authors [45] reported a high total MB removal efficiency of 97% (adsorption in the dark for 2 h, followed by photodegradation under UV for 4 h) for their TiO 2 -coated PDC material. Although the authors did not evaluate how much MB would be removed in a 6-h experiment without UV irradiation for comparison, they reported that the 2-h adsorption in the dark already accounted for 35% of the MB for the TiO 2 -coated samples.…”

A review on the ceramic additive manufacturing technologies and availability of equipment and materials

“…Profs. Bernardo and Colombo have been leading research in the area, mostly using preceramic silicone as the binder [68][69][70][71][72][73][74] to create scaffolds made of a variety of ceramic and glass materials with potential application in bone tissue engineering applications.…”

Defective structure of doped carbons obtained from preceramic polymers through Cl2‐ and NH3‐assisted thermolysis

“…In this sense, Bernardo and Elsayed 29,30 were pioneers in describing the evolution of a preceramic matrix based on silicon oxycarbide precursors with the incorporation of a phosphate source. The microstructure of this material was described as a glass–ceramic composite, in which the crystalline phases were finely dispersed in a C‐containing phosphorous–silicate melt 31 …”