Abstract
Cancellous bone is a composite of a biopolymer phase (type-I collagen) and a mineral phase (carbonated hydroxyapatite) assembled into a hierarchically structured, highly-porous network, which possesses proper mechanical strength. In this study, two types of ceramic-based scaffolds were synthesized to mimic the structure and mechanical performance of cancellous bone. Natural scaffold was obtained by complete deproteinization of bovine cancellous bone while synthetic scaffold of alumina was prepared by freeze casting. Both types of ceramic scaffolds were then infiltrated with a polymer phase (PMMA) by vapor deposition polymerization. Microstructural features of bio-inspired scaffolds were characterized by stereoscopy, scanning electron microscopy (SEM) and micro-computed tomography (µ-CT). Compressive tests showed that vapor deposition polymerization can successfully enhance the mechanical performance of scaffolds. Microstructural features and mechanical properties of scaffolds can be tunable by controlling the amount of monomer, cooling rate as well as grafting and annealing treatments. The compressive strength of scaffolds increased with increasing cooling rate and the amount of monomer applied. Toughening mechanisms at the ceramic/polymer interface, such as crack deflection, uncracked ligament bridging and microcrack formation were observed and discussed.