One-pot preparation of inorganic-organic double-shell microcapsule with good barrier and mechanical property via photopolymerization

Abstract

Microcapsule has been widely used for fabricating functional coatings. For practical application in coatings, an ideal microcapsule should possess outstanding barrier, thermal and mechanical properties simultaneously. In this paper, a series of double-shell hybrid microcapsule loaded with self-healing agent (linseed oil, LO) with outer inorganic SiO2 shell and inner UV-cured polymeric shell were successfully synthesized via photopolymerization. The obtained double-shell hybrid microcapsule was characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The barrier properties, thermal stability and mechanical property of the microcapsules were investigated in detail. Via the adjustment of chemical structure of photo-curable resin and the crosslinking density, the core release of the microcapsule could be reduced to only 2.5 wt% after immersing in organic solvent for 48 h, suggesting the outstanding barrier properties of the double-shell microsphere. The double-shell hybrid microcapsules also possessed outstanding thermal stability, and its initial decomposition temperature increased by about 32 ℃ and 14 ℃ compared with that of mono-shell organic and inorganic microcapsules. Moreover, the Young's modulus and hardness of the double-shell hybrid microcapsules were thirty-fold and forty-fold that of mono-shell organic microcapsules, which proved their excellent mechanical property. And the prepared double-shell hybrid microcapsule could encapsulate LO stably for a long time to avoid its failure, which was successfully employed to the construction of self-healing coatings.