Keywords: polymethylmethacrylate, PMMA bone cement, joint replacement, autonomic healing, fracture toughness, polymerisation, crystal size, biomaterials
An autonomically-healed PMMA bone cement: influence of the crystal size of Grubbs' catalyst on fracture toughness and polymerisation rate
In this study, it was shown that the concept of autonomic healing of a neat polymeric material, which was introduced by White et al. (2001) could be applied to poly methyl methacrylate (PMMA) bone cement. The bone cement brand used – Surgical Simplex®P – is one that is widely used in cemented arthroplasties; the healing agent used was 2.0 wt.% dicyclopentadiene (DCPD), encapsulated in poly (urea-formaldehyde) microspheres (diameter = 226 ± 51 μm) and the catalyst used was 0.25 wt.% first-generation Grubbs' catalyst. The microspheres and the catalyst were blended with the cement's powder in a mortar bowl using a polymeric spatula and the blended powder mixture and the cement's liquid monomer were mixed under a partial vacuum. Autonomic healing of the cement was demonstrated through a comparison of the values of the plane-strain fracture toughness (KIC) of the control cement (no healing agent or catalyst included in the powder) and the cement in which the powder contained DCPD and Grubbs' catalyst. For the autonomically-healed cement, (KIC) was not significantly influenced by the size of the individual crystals of the Grubbs' catalyst (mean diameter, DG), but the estimated polymerisation rate of the curing cement at 37°C, increased significantly with decrease in DG.