Acid-catalyzed moisture-curing polyurea/polysiloxane ceramer coatings

The pam-toluene sulfonic acid (p-TSA) was used to catalyze the moisture cur ing of an organic/inorganic hybrid coating system. The organic phase was ba sed on the isocyanurate of 1,6-hexamethylene of diisocyanate (HDI). The ino rganic phase was based on the prepolymerized oligomers of tetraethyl orthos ilicate (TEOS). An alkoxysilane-functionalized HDI isocyanate was added int o the coating formulation to aid in phase miscibility. The general coating and tensile properties were evaluated as a function of the acid catalyst co ncentration. In addition, the films were analyzed using differential scanni ng calorimetry (DSC) and dynamical mechanical thermal analysis (DMTA). The results indicated that the acid catalyst enhanced the adhesive properties o f the hybrid coatings. The addition of the acid catalyst increased the chan ged crosslink density of films and decreased the crystallinity of the organ ic phase. (C) 2000 Elsevier Science S.A. All rights reserved.