Development of a dual capsule self‐healing silicone composite using silicone chemistry and poly(melamine‐urea‐formaldehyde) shells

Abstract This study aims to develop microcapsules that can be used as room‐temperature self‐healing agents in silicone‐based matrices. A telechelic reactive silanol‐terminated polydimethylsiloxane (PDMS) as the healing agent, was selected to ensure the homogeneity of the polymeric matrix and encapsulated in poly(melamine‐urea‐formaldehyde) shells through an in‐situ emulsion polymerization technique. To catalyze the polycondensation reaction of the healing agent, dibutyltin dilaurate (DBTL) was encapsulated within the same type of polymeric shell. The synthesized microcapsules were characterized using Fourier‐transform infrared spectrometry, optical microscopy, scanning electron microscopy (SEM), and differential scanning calorimetry. The analyses confirmed that the spherical microcapsules with an average size of 56 μm for PDMS‐MUF microcapsules and 42 μm for DBTL‐MUF microcapsules, with a shell wall thickness of 100–200 nm, and good thermal stability were formed. Therefore, the two‐component self‐healing silicone composite was successfully developed using 10:1.2 wt% PDMS: DBTL microcapsules within the silicone matrix. SEM showed the self‐healing ability of the silicone matrix by observing the successful healing of microcracks at room temperature. Tensile and trouser tear tests were adopted to assess the self‐healing performance of the elastomeric matrix, showing the self‐healing efficiencies of 67% and 55%, respectively.