Multinuclear Solid-state NMR Investigation of Nanoporous Silica Prepared by Sol-gel Polymerization Using Sodium Silicate

Abstract

Multinuclear solid-state nuclear magnetic resonance (NMR) experiments were performed to investigate the local structure changes of nanoporous silica during hydrothermal treatment and surface modification with 3-aminopropyltriethoxysilane (3-APTES). The nanoporous silica was prepared by sol-gel polymerization using inexpensive sodium silicate as a silica precursor. Using 1 H magic angle spinning (MAS) NMR spectra, the hydroxyl groups, which play an important role in surface reactions, were probed. Various silicon sites such as Q 2 , Q 3 , Q 4 , T 2 , and T 3 were identified with 29 Si cross polarization (CP) MAS NMR spectra and quantified with 29Si MAS NMR spectra. The results indicated that about 25% of the silica surface was modified. 1 H and 29 Si NMR data proved that the hydrothermal treatment induced dehydration and dehyroxylation. The 13 C CP MAS and 1 H MAS NMR spectra of 3-APTES attached on the surface of nanoporous silica revealed that the amines of the 3-aminopropyl groups were in the chemical state of NH 3 + rather than NH 2 .

Design of a Zn Single-Site Curing Activator for a More Sustainable Sulfur Cross-Link Formation in Rubber

“…However, both the latter two resonances can be related also to amino species such as −NH 3 + and −NH 2 , respectively, in agreement with the line shape of C2 resonance in the 13 C CPMAS spectrum, previously discussed. , The same pattern was detected for Zn Y A 1/2 -SiO 2 proton spectra, except for the disappearance of the 1.9 and 5.2 ppm sharp peaks and the increase of both the bands at 7.3 and 4.6 ppm. In agreement with Kim et al, this behavior can be related to the interaction of the zinc ions with the amino groups, thus confirming their effective coordination with the anchored APTES molecules.…”

Water-Dispersible Silica-Coated Upconverting Liposomes: Can a Thin Silica Layer Protect TTA-UC against Oxygen Quenching?

“…A-UL-D consisted of a mesh of spherical-polygonal particles within the same size range as the water dispersed A-UL particles observed by TEM. The 29 Si NMR spectrum (Figure S8) shows a broad peak at −68 ppm, corresponding to the fully condensed (T 3 ) organosilica product of APTES. , In comparison, ApT-UL-D had a more coarse structure, and individual particles could not be distinguished. This is consistent with the hypothesis that ApT-UL particles are embedded in a matrix of amorphous silica.…”

Silylation of saponite with 3-aminopropyltriethoxysilane

“…59 (C5), 46 (C3), 28 (C2), 19 (C4), and 8.6 (C1) ppm (Kallury et al, 1994;Kim et al, 2011). The silylated Sap showed signals at 10.5, 22.4, and 42.8 ppm, corresponding to C1, C2 and C3, respectively (Fig.…”