Abstract
Porous composites are widely applied in various fields due to their lightweight, high surface/volume ratio and energy absorbing ability. Natural porous composites, such as bird feathers, beaks and bones, possess lightweight and superior mechanical properties due to their anisotropic, hierarchically porous structure. In this study, we synthesized ultra-lightweight, multifunctional scaffolds mimicking natural porous composites by the freeze casting technique utilizing diatomaceous earth (DE) as raw materials. By controlling the cooling rate, sintering condition and the formation of ice dendritic structures, scaffolds with aligned micro-scaled channels and nano-scaled pores were synthesized. Structural characterization was carried out by SEM and the compositional analysis was identified by XRD. Mechanical properties of DE scaffolds were measured by compressive tests and compared with silica scaffolds. Results showed that two scaffolds had similar ultimate compressive stress and elastic modulus yet DE scaffolds have better toughness and deformability. DE scaffolds were further infiltrated by polymer (PVA) to improve their mechanical properties. The water adsorption, water retention and thermal conductivity of DE scaffolds were also evaluated. The bio-inspired, hierarchically porous scaffolds can be further modified and applied in different fields.