6.3 Flexible Bonding and Sealing
6.3.1 Silane-Modified Polymers
Silane-modified polymers (SMPs) or silyl-terminated polymers (STPs) possess an organic polymeric backbone (polyethers, PUs) terminated with reactive alkoxysilanes19. These adhesives are formulated with room temperature cure catalysts. SMPs start curing when exposed to atmospheric moisture and form an elastic crosslinked polymer. When the SMP has a polymeric backbone of polyethers, the system is known as a modified silicone (MS) polymer. When the polymeric backbone is PU-based, it is known as a silyl-modified polyurethane (SPUR) polymer; both are a subclass of SMPs as they have similar chemistry and features. SMPs combine the strength of PUs/polyether with the environmental resistance of silicones20. In addition to their high-performance properties, this product family has gained popularity due to its solvent-free and isocyanate-free nature. Because of the similarity of their polymer backbones, collectively, these polymers are generally referred to as SMPs. SMPs, upon curing, always release methanol or ethanol as a by-product; thus, they are neutral cure technology.