Acetone-induced polymerisation of 3-aminopropyltrimethoxysilane (APTMS) as revealed by NMR spectroscopy.
We followed the reactivity of acetone with 3-aminopropyltrimethoxysilane, a potential organosilane coupling agent, by (1)H, (13)C and (29)Si NMR spectroscopy. Selective 1D and 2D-edited NMR experiments significantly contributed to simplify the spectral complexity of reaction solution and elucidated molecular structures within progressive reaction phases. The course of the 3-aminopropyltrimethoxysilane reaction with acetone was shown by a progressive decrease of both reactants, and a concomitant appearance of water and methanol, due to formation of imine and hydrolysis of alkoxysilane groups, respectively. The occurrence of multiple siloxane linkages in a progressively larger cross-linked macromolecular structure was revealed by DOSY-NMR experiments and new signals in (29)Si-NMR spectra at different reaction times. The NMR approach described here may be applied to investigate the reactivity of other γ-aminopropylalkoxysilanes and contribute to define procedures for the preparation of silica-based materials.
Centro Interdipartimentale per la Risonanza Magnetica Nucleare, Università di Napoli Federico II, Via Università 100, 80055, Portici, Italy.
Pierluigi
P
Mazzei
Luigi
L
Fusco
Alessandro
A
Piccolo
13C; 1H; 29Si; 3-aminopropyltrimethoxysilane (APTMS); DEPT-HMQC; DOSY; HMQC-TOCSY; NMR; polymerisation; selective excitation