Self-healing chemistry used for damage repair have not previously been demonstrated for free-radical polymerization pathways. However, this chemistry is important for addition polymers such as poly(methyl methacrylate) used in bone cement and epoxy vinyl ester used in dental resins. Self-healing biomaterials offer the potential for safer and longer lasting implants and restoratives by slowing or arresting crack damage. In the free-radical self-healing system reported here, the three components required for polymerization (free-radical peroxide initiator, tertiary amine activator, and vinyl acrylate monomers) are compartmentalized into two separate microcapsules-one containing the peroxide initiator, and the other containing both monomer and activator. Crack damage ruptures the capsules so that the three components mix and react to form a new polymer that effectively rebonds the crack and restores approximately 75% of the original fracture toughness. Optimal healing is obtained by a systematic evaluation of the effect of monomer, initiator, and activator concentration on healing performance.

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