Preparation and properties of self-healing microcapsules containing an UV-curable oligomers of silicone

In this work a new series of microcapsules for self-healing coatings were successfully prepared by an in-situ polymerization route with poly (urea-formaldehyde) (PUF) as a shell material and a mixture of methacryloxypropyl terminated dimethyl silicone oil (2MA4000) and 1-hydroxycyclohexyl phenyl ketone (I-184) as core materials. The UV curing properties of the core materials were performed by the gel yield. The surface morphology and shell wall thickness, the particle size and distribution, and the chemical structure and properties of microcapsules were characterized by SEM, FTIR, laser particle size analyzer and thermogravimetric analysis (TGA). The results indicated that the gel yield of 2MA4000 with 3 wt.% Irgacure-184 was 63.35%. The spherical microcapsules (particle size of mostly 20-50 μm) were produced with a relatively thin shell wall of 20-90 nm, a filling content of 84 wt.%, and a high yield of 71.4 wt.%. The microcapsules exhibit a good heat resistance. The core of the microcapsule was under a good preservation state during the encapsulated process, and part of the core which was in the interface between oil and water participated in the reaction of urea and formaldehyde. It makes the microcapsule wall being the organosilicon modified PUF resins, which promotes the thermostability of the microcapsule wall and compatibility with organosilicon coating.