A Self-healing PMMA Bone Cement: Influence of Crystal Size of Grubbs' Catalyst

摘要

In the present study, we demonstrated room-temperature self-healing functionality in a commercially-available poly (methyl methacrylate) (PMMA) bone cement brand that is widely used in the fixation of total joint replacements (TJRs); namely, Surgical Simplex~RP. The healing agent used was dicyclopentadiene (DCPD) (2.0 wt.%), encapsulated in poly (urea-formaldehyde) microspheres (diameter = 226 ± 51 (im). Two variants of a first-generation Grubbs' catalyst (0.25 wt.%) were used, with the difference being in the cross-sectional area of the individual crystals, AG. The microspheres and the catalyst were blended with the cement's powder, and the blended powder mixture and the cement's liquid monomer were mixed under a partial vacuum. The three study groups were: control (no healing agent or catalyst blended with the cement powder); Preparation I (DCPD + Grubbs' catalyst with A_G of ~ 2000 μm~2 blended with the cement powder); and Preparation II (DCPD + Grubbs' catalyst with A_G = ~ 20 Jim2 blended with the cement powder). Self-healing in Preparation I and II group specimens was demonstrated through significantly lower fatigue crack propagation (FCP) rates in these specimens compared to that of the control group specimens. For the self-healing cements, the estimated polymerization rate of the curing cement, at 37 °C, as determined from the results of differential scanning calorimetry tests, increased significantly with decrease in A_G.