B. Lebeau, J. Maquet, C. Sanchez, F. Beaume and F. Lauprêtre
Hybrid siloxane–silica coatings have been prepared by hydrolysis and condensation ofN -[3-triethoxysilylpropyl]-2,4-dinitrophenylamine (TSDP) and tetramethoxysilane (TMOS) precursors. Hetero- and homo-condensations between both precursors have been demonstrated to occur in the early stages of the process via 17O and 29Si nuclear magnetic resonance (NMR) in solution. These hybrids can be described as nanocomposites made of polysiloxane-based domains cross-linked by silica-based nanoparticles, as evidenced by solid-state NMR, differential scanning calorimetry (DSC) and Fourier-transform infrared (FTIR) studies. Moreover, the high degree of interpenetration occurring in these materials is evidenced by the presence of some Q and T subunits sequestered within these polysiloxane and silica-based domains, respectively. The high-resolution solid-state 13C NMR technique has shown that the mobility of the propyl 2,4-dinitrophenylamine chromophores is correlated with the glass-transition phenomenon of the matrix.