The development of functional foams preparation would gain impressive progress by mimicking the structural organisation of strong trabecular bones. Sodium silicate solutions, so-called water-glass (WG), offer the possibility of making foams directly during sintering due to the evaporation of water. Prior studies have shown that WG coatings enable to enhance osseointegration between implants and tissue and modulate resorption rate of the substrate material. Therefore, WG-foam could be a promising candidate for hierarchical implant applications.
Here we report on a cost-effective and straightforward process to produce three-dimensional, highly porous and mechanically resilient WG-foams by microwave heating. The process parameters modulate the interconnectivity and size of the pores. We present a comprehensive study of the foam characteristics in 2D and 3D, which we evaluated by combining X-ray diffraction, scanning electron microscopy and micro-computed tomography. The compressive strength achieved by our foams is in the range of and even above the values reported by Bioglass® foams. In simulated body fluid, we observe degradation and formation of hydroxyapatite. By correlating the processing parameters with the structural properties of our final products, we better understand the foaming mechanism which allows us to design products with defined porosity and mechanical properties.
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