Synthesis and Characterization of Urea-formaldehyde Microcapsules Containing Functionalized Polydimethylsiloxanes

Self-healing anticorrosive coatings require healing agents with hydrophobic properties and low glass transition temperature. Polydimethylsiloxanes are group of compounds with high degree of hydrophobicity and very low glass transition temperatures. The nature of functional group of core material highly affect the properties of resultant microcapsules. Therefore, in this work, three polydimethylsiloxanes with different functional groups were successfully encapsulated in urea-formaldehyde microcapsules for self-healing applications through oil-in-water (OIW) emulsion polymerization. The resultant microcapsules were analyzed via Fourier transformed Infrared spectroscopy (FT-IR) for structural confirmation, thermogravimetric analysis (TGA) for the thermal behaviour, scanning electron microscopy (SEM) for size and morphology, and electron dispersive spectroscopy (EDS) for the elemental composition. For OH and vinyl terminated PDMS, microcapsules had diameters in the range of 100 to 500 μm while for Epoxy terminated PDMS microcapsules diameters were in the range of 50 to 100 μm. Thermal degradation behaviour was also different for all kinds of microcapsules, showing that nature of core materials affect the properties of microcapsules.