Amino surface functionalized microcapsules as curing agents for polyurethane foams

This work regards the manufacturing process and assessment of amino surface functionalized microcapsules (MCs) containing glycerol in their core, for application in one-component polyurethane (PU) foams to act as a sustainable curing catalyst. Microemulsion techniques combined with sol-gel processing, involving the development of specific steps during the synthesis, were found to enable this type of functional active microparticles. The MCs should only burst and release their content at the spraying stage, in order to assist and promote an accelerated curing of the foam. It has been found that the surface treatment employed in the last step of inorganic silica MCs synthesis procedure, using an amino silane, led to the best curing performance for PU foams. In fact, the amino functionalized MCs exhibited a more perfect spherical format and less aggregation than the inorganic MCs, did not exhibit significant leaching, and led to a significant increase in the curing rate of the PU foam. The study involved characterization techniques, such as scanning electron microscopy, Fourier transformed infrared spectroscopy, thermal gravimetric analyses, leaching, and curing speed evaluation.