Highly Porous Polymer-Derived Bioceramics Based on a Complex Hardystonite Solid Solution

Hamada Elsayed; Michele Secco; Federico Zorzi; Katharina Schuhladen; Rainer Detsch; Aldo R Boccaccini; Enrico Bernardo

doi:10.3390/ma12233970

Highly Porous Polymer-Derived Bioceramics Based on a Complex Hardystonite Solid Solution

Materials (Basel). 2019 Nov 30;12(23):3970. doi: 10.3390/ma12233970.

Authors

Hamada Elsayed^{1

2}, Michele Secco³, Federico Zorzi⁴, Katharina Schuhladen⁵, Rainer Detsch⁵, Aldo R Boccaccini⁵, Enrico Bernardo¹

Affiliations

¹ Department of Industrial Engineering, Universita degli Studi di Padova, 35131 Padova, Italy.
² Ceramics Department, National Research Centre, 12622 Cairo, Egypt.
³ Department of Civil, Environmental and Architectural Engineering (ICEA) and Inter-Departmental Research Center for the Study of Cement Materials and Hydraulic Binders (CIRCe), University of Padova, 35131 Padova, Italy.
⁴ Department of Geosciences, University of Padova, 35131 Padova, Italy.
⁵ Institute of Biomaterials, Department of Materials Science and Engineering, University of Erlangen-Nuremberg, 91058 Erlangen, Germany.

Abstract

Highly porous bioceramics, based on a complex hardystonite solid solution, were developed from silicone resins and micro-sized oxide fillers fired in air at 950 °C. Besides CaO, SrO, MgO, and ZnO precursors, and the commercial embedded silicone resins, calcium borate was essential in providing the liquid phase upon firing and favouring the formation of an unprecedented hardystonite solid solution, corresponding to the formula (Ca_0.70Sr_0.30)₂(Zn_0.72Mg_0.15Si_0.13) (Si_0.85B_0.15)₂O₇. Silicone-filler mixtures could be used in the form of thick pastes for direct ink writing of reticulated scaffolds or for direct foaming. The latter shaping option benefited from the use of hydrated calcium borate, which underwent dehydration, with water vapour release, at a low temperature (420 °C). Both scaffolds and foams confirmed the already-obtained phase assemblage, after firing, and exhibited remarkable strength-to-density ratios. Finally, preliminary cell tests excluded any cytotoxicity that could be derived from the formation of a boro-silicate glassy phase.

Keywords: 3D printed scaffolds; biosilicate ceramics; direct ink writing (DIW); foams; hardystonite; polymer derived ceramics (PDCs).