Thermal and mechanical behaviour of self-curable waterborne hybrid polyurethanes functionalized with (3-aminopropyl)triethoxysilane (APTES)

Two series of self curable polyurethanes were synthesized using an aliphatic diisocyanate (isophorone diisocyanate), an anionic diol (2-bis(hydroxymethyl) propionic acid) and two different soft segments poly(1,4-butylene adipate) end capped diol (semicrystalline polyester) and poly (propylene glycol) end capped diol (amorphous polyether). In both cases the polyurethanes were end-capped with (3-aminopropyl) triethoxysilane to impart the films the ability to crosslink at room temperature. The thermal and mechanical properties of the cured films can be tailored with the alkoxysilane concentration. Thus, as the alkoxysilane content increases, the resulting systems present a higher degree of phase separation, according to both DSC and DMTA results. In addition, TGA results confirm that their thermal stability also increases and finally, the modulus increases and the strain decreases as a function of the cross-linking degree.