Synthesis of room temperature self-curable waterborne hybrid polyurethanes functionalized with (3-aminopropyl)triethoxysilane (APTES)

Room temperature self-curable silanized waterborne polyurethanes (Si-WPU) were synthesized by means of the acetone process employing covalently linked (3-aminopropyl)triethoxysilane (APTES) as curing agent. The insertion of this curing agent was confirmed using FTIR spectroscopy, liquid NMR and elemental analysis. The APTES concentration induced an increase of particle size, this effect being more pronounced at higher concentrations due to the condensation of the alkoxysilane groups. The condensation of silanol groups was evidenced by means of TEM, FTIR and SEM measurements. The presence of silanol groups on the particle surface was demonstrated by ς-potential analyses. Finally, the curing process of the dispersions was followed by means of gel content measurements, solid-state 29Si-NMR and FTIR studies. All the samples were able to cure at room temperature, and the extent of curing was dependent on the APTES concentration and curing temperature.