Design of hybrid organic–inorganic materials through their structure control: The case of epoxy bearing alkoxides

Hybrid organic–inorganic materials from (3-glycidoxypropyl)methyldiethoxysilane (GPMD) and [3-(2-aminoethyl)aminopropyl]trimethoxysilane (AEAPTMS) have been synthesized. The structure of the hybrid material has been studied as a function of AEAPTMS content by a combination of vibrational and nuclear magnetic resonance spectroscopies. The amine groups in AEAPTMS have shown to be very effective epoxy curing agents and the degree of condensation inside the hybrid material can be finely tuned with the amount of AEAPTMS. Fourier transform near infrared spectroscopy coupled with 2D infrared analysis has been used to elucidate the role of amines in epoxy curing. Several reactions of the amines with the epoxies have been observed, via tertiary, secondary and primary amines. At low AEAPTMS contents the hybrid material exhibits a residual mobility of the organic species, as revealed by solid state NMR spectroscopy. This property has been evaluated comparing qualitatively the residual mobility in hybrid materials synthesized with different types of organically modified alkoxides containing epoxy functional groups.