Natural tissue can self-heal and regenerate. However, when subjected to large defects or trauma, surgical intervention are needed for tissue restoration. For repairing load bearing tissue such as bone, such scaffold needs to act as a temporary template for tissue and satisfy requirements such as appropriate mechanical properties, degradation rate that matches growth of tissue and biocompatibility. Class II polymer/silica hybrids are interpenetrating networks of inorganic and organic components that interact at the nanoscale, and they can be designed to have tailorable mechanical properties and degradation rates. The aim of this thesis was to incorporate poly(ε-caprolactone) (PCL), a biodegradable polymer, into the synthesis of polymethacrylate/silica hybrids which were previously synthesised in non-degradable formulations. Despite the high tailorability of polymethacrylate/silica hybrids, they were brittle at fracture and too stiff compared to natural tissue. This thesis aimed to improve the elasticity of the hybrids.
In this thesis, novel di-block PCL-b-(butyl methacrylate-co-(3-(trimethoxysilyl)propyl methacrylate))/silica hybrids and PCL-b-(butyl methacrylate-co-methyl methacrylate-co-(3-(trimethoxysilyl)propyl methacrylate))/silica hybrids were successfully synthesised. The polymers were synthesised via reversible addition-fragmentation chain transfer (RAFT) polymerisation, and biodegradability was achieved by limiting the molecular weight of the non-degradable block to under 30 kDa. The hybrids showed highly tailorable mechanical properties that covered typical range of mechanical properties of cortical bone and trabecular bone. All hybrids showed viscoelastic characteristics and were able to take cyclic loading across a small strain range (< 5.5%). All compositions exhibited pronounced strain-hardening behaviour before fracture, and ductile failure was experienced by some of the compositions with 85 wt% organic content. The hybrids achieved significantly lower Young’s Modulus and lower ultimate compressive strength, as well as higher deformation at failure compared with previously reported polymethacrylate/silica hybrids. Biological characterisation confirmed non-toxicity via a three-day viability test, and the hybrid surface was proven to support cell attachment and proliferation.