Microcapsules filled with reactive solutions for self-healing materials

• Published in: Polymer (Guilford) 2009-02, Vol.50 (4), p.990-997
• Main Authors: Blaiszik, B.J., Caruso, M.M., McIlroy, D.A., Moore, J.S., White, S.R., Sottos, N.R.
• Format: Article
• Language: English
• Subjects: Applied sciences; Autonomic materials; Exact sciences and technology; Forms of application and semi-finished materials; Microcapsules; Miscellaneous; Polymer industry, paints, wood; Self-healing; Technology of polymers
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2008.12.040

Microcapsules containing a solvent and reactive epoxy resin are a critical component for the development of cost-effective, low toxicity, and low flammability self-healing materials. We report a robust in situ encapsulation method for protection of a variety of oil soluble solvents and reactive epoxy resins surrounded by a thin, polymeric, urea–formaldehyde (UF) shell. Resin–solvent capsules are produced in high yield with diameters ranging from 10 to 300μm by controlling agitation rates. These capsules have a continuous inner shell wall and a rough exterior wall that promotes bonding to a polymer matrix. Capsules as small as 300nm in diameter are achieved through sonication and stabilization procedures. The presence of both the epoxy resin and solvent core components is confirmed by differential scanning calorimetry (DSC) measurements, and the relative amount of epoxy and solvent in the liquid core is determined by thermogravimetric analysis (TGA). The capsules are shown to satisfy the requirements for use in self-healing materials including processing survivability, thermal stability, and efficient in situ rupture for delivery of healing agent. [Display omitted]