Microencapsulation of liquid cyanoacrylate via in situ polymerization for self-healing bone cement application
Structural polymers are susceptible to accumulated damage in the form of internal microcracks that propagate through the material, resulting in mechanical failure. Self- healing approaches offer a solution to repair these damages automatically. The first generation selfhealing material system includes a microencapsulated healing agent within a catalyst-embedded matrix. Propagating microcracks rupture the microcapsules, releasing the liquid healing agent into the damaged region. Catalyst-triggered polymerization of the released healing agent repairs the damage. Our research focuses on a similar approach for addressing "damage accumulation failure" of poly(methyl methacrylate) (PMMA) bone cement caused by microcrack initiation and propagation. In this study, polyurethane (PU) microcapsules containing a tissue adhesive, 2-octylcyanoacrylate (OCA) were synthesized using in situ interfacial polymerization of toluene-2,4-diisocynate (TDI) and polyethylene glycol 200 (PEG 200) through an oil-in-oil-in-water microemulsion (o/o/w). The process was optimized by studying different combinations of organic solvents, surfactants, temperatures, agitation rates, pH, and reaction times and their effects on microencapsulation were observed. Microcapsule surface morphology, size, shell thickness, encapsulated OCA viability, thermal degradation, and chemical structure of the microcapsule shell were evaluated using a stereoscope, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and fourier transform infrared spectroscopy (FT-IR). © 2012 Materials Research Society.
