Direct Ink Writing of a Preceramic Polymer and Fillers to Produce Hardystonite (Ca₂ZnSi₂O₇) Bioceramic Scaffolds

Abstract

The direct ink writing of an ink composed of a preceramic polymer and fillers was used to produce hardystonite (Ca2ZnSi2O7) bioceramic scaffolds. Suitable formulations were developed for the extrusion of fine filaments (350 μm diameter) through a nozzle. The preceramic polymer was employed with the double purpose of contributing to the rheology of the ink by increasing its viscosity and of forming the hardystonite phase upon heat treatment by reacting with the fillers. A control of the rheology is essential when spanning features have to be produced, and therefore the main rheological characteristics of the inks were measured (flow curves, dynamic oscillation tests, viscosity recovery tests) and compared to models reported in the literature. Highly porous scaffolds (up to 80% total porosity) were produced and heat treated in air or in nitrogen atmosphere. The influence of the heat-treatment atmosphere on the morphology, crystalline phase assemblage, and compressive strength of the scaffolds was investigated

Biosilicate® scaffolds produced by 3D‐printing and direct foaming using preceramic polymers

“…From the TG plot of preceramic polymer and fillers (formulation G0 (100% PDC), with MK), shown in Figure , we can note a substantial overall weight loss. The most significant mass loss stages were detected at 510‐520°C and 710‐720°C, and they were attributed to the overlapping of silicone polymer‐to‐ceramic conversion and both Na and Ca carbonate decompositions (known to occur above 500°C and above 650°C, respectively). The exothermic effects of the burn‐out of organic moieties probably “masked” the endothermic effect (not detected) of carbonate decomposition.…”

“…To obtain an ink suitable for 3D printing experiments (starting from G0 formulation) MK silicone was first dissolved in 27.5 vol.% of isopropanol alcohol (C 3 H 8 O, 2‐Propanol, HPLC BASIC, Scharlau, Scharlab Italia srl, Riozzo di Cerro al Lambro [MI], Italy) and then mixed with nano‐sized fumed silica (FS; SiO 2, Aerosil R106; Evonik, Essen Germany), average primary particle size was 7 nm, and BET surface area was 220‐280 m 2 /g (specified by the supplier). The introduction of fumed silica was intended to modify the rheological properties, particularly to provide a pseudoplastic behavior with yield stress, suitable for the printing of suspended struts . According to previous experiences, fumed silica had an optimum impact, as a rheology modifier, by partially replacing the silicone resin as silica source, for an amount of 10 wt.% of the total silica content.…”

Organosilicon polymer-derived ceramics: An overview

“…Silicate ceramics are often used as cements, concrete, bioceramics, etc. [18,[90][91][92][164][165][166][167][168][169][170]. Among them, calcium-based silicate ceramics have been developed for biomedical applications due to their excellent bioactivity [171][172][173].…”

The In Vitro Bioactivity, Degradation, and Cytotoxicity of Polymer-Derived Wollastonite-Diopside Glass-Ceramics

“…In fact, recent experiences have shown the feasibility of reticulated scaffolds by the direct ink writing (also known as “robocasting”, i.e., direct 3D-printing) of silicone-based pastes, as well as by powder 3D-printing (ink jet writing) on pure silicone or silicone-fillers [25,29,30,31]. …”