Synthesis of polylactide-ceramic microparticles as potential bone substitution material for selective laser melting (SLM)

Jens Nelsen, University of Duisburg-Essen, Essen, Germany
Gregor Doerdelmann, University of Duisburg-Essen, Essen, Germany
Rosario Lizio, Evonik Corporation, Birmingham, Alabama
Rafael Gentsch, Evonik Corporation, Birmingham, Alabama
Harsh Patel, Evonik Corporation, Birmingham, Alabama
Tommy Washington, Evonik Corporation, Birmingham, Alabama
Matthias Epple, University of Duisburg-Essen, Essen, Germany

A potential bone substitution material based on poly(L-lactide-co-D,L-lactide) as the organic phase with either calcium phosphate nanoparticles or calcium carbonate nanoparticles as the inorganic phase were synthesized. This polymer-ceramic microcomposite system is flowable, biodegradable and printable. Therefore, it is suitable for the additive manufacturing of bone substitution material by selective laser melting. The particles were prepared by a solid-in-oil-in-water emulsion solvent evaporation method and analyzed by scanning electron microscopy, thermogravimetry, differential scanning calorimetry, flowability investigations, cell proliferation experiments and mechanical testing.

The synthesis of the polymer-ceramic-microcomposite particles resulted in particles with an average diameter of 10-70 µm. Thermogravimetric investigations have shown a homogeneous distribution of the ceramic component inside the composites. The addition of ceramic nanoparticles, compensated the acidic degradation of polylactide, and furthermore to an enhanced proliferation of MC3T3-cells (osteoblasts) on the surface of cylinder-shaped test specimen. The addition of the ceramics also improved the mechanical properties of hot-pressed test specimen in three-point-bending. It was possible to prepare a polymer-ceramic-microcomposite material that has all necessary properties for the generative manufacturing of individually shaped bone substitution materials by selective laser melting.

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