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Solid state NMR characterization of phenylphosphonic acid encapsulated in SBA-15 and aminopropyl-modified SBA-15

2012; Elsevier BV; Volume: 166; Linguagem: Inglês

10.1016/j.micromeso.2012.04.028

1873-3093

Daniela Aiello, Nicolas Folliet, Guillaume Laurent, F. Testa, Christel Gervais, Florence Babonneau, Thierry Azaı̈s,

Advanced Battery Materials and Technologies

We present in this communication that phenyl phosphonic acid can be efficiently loaded in mesoporous SBA-15 and aminopropyl-modified SBA powdered samples through the incipient wetness impregnation method. High amount of phosphonic acid can be reach up to 380 mg/g of sample. We use multinuclear solid state NMR as a method of choice for the indeep characterization of the samples. Thus we demonstrate that phosphonic acid molecules do not crystallize inside the pores. The molecules are highly mobile in SBA-15 because they are submitted to a confinement effect due to the mesoscopic size of the pores and consequently they exhibit a weak interaction with the silica walls. In the case of aminopropyl-modified SBA material, we show that the molecules are rigid and that they are in strong interaction with the aminopropyl groups. Moreover, a 2D double quantum 1H NMR experiment recorded at high field and high spinning speed permit to propose a model of the phosphonate-aminopropyl interaction. The increase in spectral resolution due to the combination of high magnetic field and fast MAS rate allows also the assignment of 1H resonances in aminopropyl-modified SBA matrix and notably allows the assignment of the protons resonance of the amino group.