Towards a better description of organosilane grafting onto silica particles using volumetric techniques based on molecular probing

Alloul, Haytham; Roques-Carmes, Thibault; Toufaily, Joumana; Kassir, Mounir; Pelletier, Manuel; Razafitianamaharavo, Angélina; Hamieh, Tayssir; Villièras, Frédéric

doi:10.1007/s10450-016-9800-2

Cited by 9 publications

(9 citation statements)

References 60 publications

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“…As shown in Figure 4, the 29 Si MAS NMR spectrum of bare silica (SGB) shows three characteristic signals at −92, −101, and − 110 ppm, which can be attributed to Q 2 , Q 3 , and Q 4 silicon species. 20 Furthermore, octadecylmodified silica supports spectra show the presence of signals between −45 and − 70 ppm, which refer to T n species, characteristic of the attachment, and cross-linking of octadecyl groups on the silica surface.…”

Section: Characteristics Of the Octadecylmodified Silicasmentioning

confidence: 99%

“…Nuclear magnetic resonance tests were performed on an Agilent 9.4 T wide-bore magnet equipped with HXY 6 mm "pencil" solid-state NMR probe controlled by Agilent DD2 console. Probe tune and match were set in Larmor frequencies of 399.72, 100.52, 79.40 MHz for the nuclei 1 H, 13 C, and 29 Si, respectively. The sample temperature was kept constant at 30 C during all tested time.…”

Section: Solid-state Nmr Characterizationmentioning

confidence: 99%

“…The sample temperature was kept constant at 30 C during all tested time. Direct polarization MAS was carried out with 29 Si with a relaxation delay of 100 s, in 256 scans. 1 H cross-polarization MAS (CP/MAS) was realized for 13 C with 200 scans and 5 s of relaxation delay.…”

Section: Solid-state Nmr Characterizationmentioning

confidence: 99%

“…Similar results have already been reported in the literature for silicas synthesized by the sol-gel method using a lower TEOS concentration. 16 After the characterization of the octadecyl chain conformation on the silica surface, further elucidation of the chemical bonding of organosilane to the surface was obtained from 29 Si MAS NMR. This technique allows modeling the formation of siloxane bonds with the silica surface.…”

Section: Characteristics Of the Octadecylmodified Silicasmentioning

confidence: 99%

“…This technique allows modeling the formation of siloxane bonds with the silica surface. Figure 4 gives the 29 Si MAS NMR spectra of bare silica and octadecyl-modified silicas.…”

Section: Characteristics Of the Octadecylmodified Silicasmentioning

confidence: 99%

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Octadecyl‐modified silica supports for metallocene catalyst applied in ethylene polymerization

Bernardes

Zarth

Gossler

et al. 2020

J of Applied Polymer Sci

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Chemical modification of silica-based supports is an alternative route for modulating the active sites of metallocene catalysts, presenting the potential to obtain polyethylenes with improved properties. Therefore, this work investigates the effect of octadecylsilane content in silica support on the behavior of resulting supported metallocene catalysts on ethylene polymerization. For this propose, a series of octadecyl-modified silicas whit different amounts of octadecyl (ODS) groups were synthesized by a modified Stöber sol-gel method and then applied as supports for a metallocene catalyst. The supported metallocene catalysts were evaluated in ethylene polymerization and ethylene/1-hexene copolymerization reactions. Besides, studies of the growth kinetics of polyethylene particles in a gas phase reactor were performed using videomicroscopy. The octadecylsilane content in the supports was in the range of 0.2 to 1.4 mmol g −1. DRIFTS and 13 C CP/MAS NMR results showed a predominance of an all-trans octadecyl chain conformation. SEM images showed spherical particle morphology for silicas having octadecylsilane content up to 0.6 mmol g −1. The supported catalysts presented activity in ethylene polymerization in the range of 1100-1900 kg PE molZr −1 h −1 bar −1. The surface polarity of the catalyst influenced the molar mass of the resulting polyethylene. The increase of the ODS content on the silica surface led to a supported catalyst with slower kinetic behavior in the gas phase, which might be attributed to the diffusive effects of the octadecyl layer on the catalyst surface.

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Section: Characteristics Of the Octadecylmodified Silicasmentioning

confidence: 99%

Section: Solid-state Nmr Characterizationmentioning

confidence: 99%

Section: Solid-state Nmr Characterizationmentioning

confidence: 99%

Section: Characteristics Of the Octadecylmodified Silicasmentioning

confidence: 99%

“…This technique allows modeling the formation of siloxane bonds with the silica surface. Figure 4 gives the 29 Si MAS NMR spectra of bare silica and octadecyl-modified silicas.…”

Section: Characteristics Of the Octadecylmodified Silicasmentioning

confidence: 99%

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