Hydrothermal-Freeze-Casting of Poly(amidoamine)-Modified Graphene Aerogels towards CO2 Adsorption

Abstract

This article presents novel poly(amidoamine) (PAMAM) dendrimer-modified with partially-reduced graphene oxide (rGO) aerogels, obtained using the combined solvothermal synthesis-freeze-casting approach. The properties of modified aerogels are investigated with varying synthesis conditions, such as dendrimer generation (G), GO:PAMAM wt. ratio, solvothermal temperature, and freeze-casting rate. Scanning electron microscopy, Fourier Transform Infrared spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy are employed to characterize the aerogels. The results indicate a strong correlation of the synthesis conditions with N content, N/C ratio, and nitrogen contributions in the modified aerogels. Our results show that the best CO2 adsorption performance was exhibited by the aerogels modified with higher generation (G7) dendrimer at low GO:PAMAM ratio as 2:0.1 mg mL−1 and obtained at higher solvothermal temperature and freeze-casting in liquid nitrogen. The enclosed results are indicative of a viable approach to modify graphene aerogels towards improving the CO2 capture.

A Four-Step Cascade Drug-Release Management Strategy for Transcatheter Arterial Chemoembolization (TACE) Therapeutic Applications

“…In accordance with Yao, S.Z. et al (2013) [30], as shown in Figure 2A, the peak at 1712 cm −1 was replaced with a new peak at 1163 cm −1 , representing C-N binding [31]. The amine group produced a peak at 667 cm −1 .…”

“…In accordance with Ya S.Z. et al (2013) [30], as shown in Figure 2A, the peak at 1712 cm −1 was replaced with new peak at 1163 cm −1 , representing C-N binding [31]. The amine group produced a pea Following the modification of GO, the structure of AFGO was analyzed using FTIR spectroscopy and EDS to confirm it was successfully prepared.…”

Enhanced CO2 Capture of Poly(amidoamine)-Modified Graphene Oxide Aerogels with the Addition of Carbon Nanotubes

“…The density evolution for the aerogels modified with PAMAM and CNTs is depicted in Figure 1 B. The density ranged between 2.5 and 7 mg cm −3 , in agreement with similar aerogels [ 18 ]. Adding PAMAM molecules resulted in an increase in the modified aerogel density, reaching a maximum of 7 mg cm −3 for the higher content of PAMAM, which was attributed to the higher degree of functionalization.…”

“…Recently, poly(amidoamine) (PAMAM) dendrimers have gained research interest for CO 2 capture as they exhibit the advantage of a higher number of functional amine end groups that are available for cross-linking [ 15 , 16 , 17 ]. However, amongst the works on dendrimer-modified CO 2 sorbents, only a few deal with modified GO aerogels [ 18 ].…”

“…As the number of amine groups increases exponentially with dendrimer generation, one would expect the functionalization degree with dendrimer to increase. However, the shape of the dendrimer and its concentration were reported to greatly affect the sorption properties of modified GO aerogels [ 18 ]. More specifically, CO 2 capture was shown to decrease with dendrimer concentration and size due to steric hindrance, i.e., the functionalization with a smaller planar dendrimer molecule from generation 3.0 yielded better results than its larger spherical counterpart from generation 7.0 [ 20 ].…”