Synthesis of a fluorinated graphene oxide–silica nanohybrid: improving oxygen affinity

Abstract

An easy method to achieve a fluorinated graphene oxide-silica nanohybrid (GOSF) is presented. Graphene oxide (GO) was synthesized by Hummer's modified method, the GO-silica nanohybrid (GOS) was obtained via Fischer esterification, the fluorinated moiety (3-pentadecafluoroheptyl-5-perfluorophenyl-1,2,4-oxadiazole) was introduced by nucleophilic substitution operated by the hydroxyl functionalities onto the GOS surface. Full characterization of the new materials confirmed the formation of covalent bonds between the graphene oxide/silica hybrid matrix and the fluorinated moieties. The proposed methodology offers an easy way to get fluorinated carbon/silica hybrid nanomaterials avoiding the harsh reaction conditions usually involved in the preparation of fluorinated materials, and allowing the selective immobilization of specific fluorotails. Moreover, performed oxygen uptake and release kinetics showed that the introduction of fluorinated moieties increases the oxygen exchange, making the material interesting for prospective applications in the biomedical field, as oxygen delivery system, as filler for biocompatible materials, and in the preparation of membranes for the purification of water.

A green method to prepare nanosilica modified graphene oxide to inhibit nanoparticles re-aggregation during melt processing

“…After the grafting of nanosilica, the bands assigned to -OH moieties (located at 1000 cm −1 and 3000-3600 cm −1 ) decrease, as well as those attributable to carboxyl and epoxy groups, whereas in the range 1200-900 cm −1 it is possible to detect a variegated absorption band with two main peaks. The one located at 1080 cm −1 can be attributable to the overlapping of Si-O-Si, C-O-C and Si-O-C bonds (see blue-filled zone in the spectrum), while the peak centered at 1014 cm −1 can be reasonably assigned to silanols [22]. Furthermore, it is possible to recognize two bands attributable to -COOSi-bonding at 1488 cm −1 and 820 cm −1 (see orange-filled regions in GOS spectrum) [12,22,25].…”

“…The one located at 1080 cm −1 can be attributable to the overlapping of Si-O-Si, C-O-C and Si-O-C bonds (see blue-filled zone in the spectrum), while the peak centered at 1014 cm −1 can be reasonably assigned to silanols [22]. Furthermore, it is possible to recognize two bands attributable to -COOSi-bonding at 1488 cm −1 and 820 cm −1 (see orange-filled regions in GOS spectrum) [12,22,25]. Fig.…”

“…The GO spectrum collected in cross polarization C-H evidenced the presence of carboxylic functionalities at about 160 ppm and C-O (ascribed to alcohols and epoxy) at about 70 ppm [3,27]. sp 2 carbons related to the graphenic matrix are located in the range 110-150 ppm in the cross polarization spectrum but no typical peak of graphitic carbon was detected, likely because of the high distance between sp 2 carbons and the protons, thus suggesting a high degree of oxygen-functionalization and the presence of a variegated aromatic environment, constituted by ketones, lactols and small graphenic domains [22]. On the other hand, the presence of silica nanoparticles covalently linked to the GO lamellae, did not allow collecting for GOS a C-MAS spectrum via cross polarization, hence the spectrum reported was obtained in direct polarization on 13 C. GOS spectrum shows the presence of a very intense signal located at 110 ppm, related to the C sp 2 resonance, and a broad signal located at 59 and 71 ppm, mainly attributed to C-O-C, thus confirming that most of alcoholic, epoxy and carboxylic moieties reacted with silica.…”

“…GO was synthesized via oxidation and subsequent chemical exfoliation of graphite by slightly modifying Tour's method [21], more details about the synthesis are reported elsewhere [22].…”

The Effects of Nanoclay on the Mechanical Properties, Carvacrol Release and Degradation of a PLA/PBAT Blend

“…Moreover, a band at 1712 cm −1 can be attributed to C=O stretching, whereas the absorption band at 1455 cm −1 may refer to scissoring of -CH 2 groups, and the modes located at 1412 cm −1 and 1378 cm −1 could be ascribed to C=C bonds typical of PBAT [26]. Furthermore, those centered at 1273, 1163, 1117, and 1104 cm −1 can be assigned to C-O stretching, while those located at 1016, 931, 867, and 729 cm −1 could refer to C-H bending [27][28][29][30]. The presence of carvacrol can be detected by monitoring the signal centered at~812 cm −1 due to the characteristic aromatic ring of a polyphenol [23][24][25].…”