Influence of Alkyl Peptidoamines on the Structure of Functionalized Mesoporous Silica

The functionalization of mesoporous silica materials with alkyl peptidoamines by the co-condensation method was investigated. Alkylpeptidoamines were introduced via (aminopropyl)triethoxysilane (APTES). Samples were prepared by using a nonionic fluorinated surfactant CF 3 (CF 2 ) 7 C 2 H 4 (OC 2 H 4 ) 9 OH. Results obtained by SAXS and nitrogen adsorption−desorption analysis clearly showed that the channel arrangement of the recovered materials depends not only on the organosilane/(organosilane+tetramethyl orthosilicate) molar fraction but also on the nature of the functional groups. Indeed, materials functionalized with BOC-Phe-APTES or with small amounts of BOC-Glu(αOBn)-βAla-APTES exhibit a hexagonal channel array. Higher BOC-Glu(αOBn)-βAla-APTES loading leads to a wormhole-like mesostructure. Whatever the organosilane/(organosilane+tetramethyl orthosilicate) molar fraction, only disordered structures are recovered when functionalization is performed with Z-Asp(αOBn)-APTES. Moreover, the pore wall thickness is strongly affected by the structure of the organic groups. The efficiency of the functionalization was evidenced by FTIR and solid state 29 Si and 13 C MAS NMR spectroscopies. Results obtained from solid state 29 Si NMR also show that polymerization rates of organosilane and tretramethyl orthosilicate must be very close to each other.