Influence of bio‐resource‐derived graphene oxide on the mechanical and thermal properties of poly(vinyl alcohol) nanocomposites

Abstract

The present study reports on an environment‐friendly and economically viable method of synthesizing graphene oxide (GO) using agricultural waste, specifically oak (Quercus ilex) fruit. The agricultural waste‐derived GO (AGO) is further used as a reinforcing filler in the fabrication of poly(vinyl alcohol) (PVA) polymer nanocomposites by employing a solution‐mixing process. A series of characterization methods have been used to assess the interactions between AGO and PVA, including, Raman spectroscopy, FT‐IR, field emission scanning electron microscopy (FESEM), and energy‐dispersive x‐ray (EDX). The thermal and structural properties have been studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA)analysis, and a universal testing machine (UTM). The strong H‐bonding interaction between the PVA interface and AGO considerably enhanced interfacial dispersion and adhesion. As a result, the addition of 5 wt% AGO to the PVA polymers significantly improved their mechanical and thermal properties, including tensile strength which rose by 117%, melting temperature (Tm) by 7.02°C, and crystallization temperature (Tc) by 9.06°C. The thermal decomposition temperatures such as T5%, T10% and T50% were increased by 53.68°C, 68.49°C, and 57.37°C, respectively. The results show that a small loading of nanofillers causes substantial increases in the thermal and mechanical properties of PVA, thus making it a promising material for structural applications.

Aptamer-Functionalized Hydrogel Biosensor Targeting Trace Antibiotics via UV Detection

“…Definitely, the above interactions among GO, PVA, and the aptamer could be confirmed by FT-IR results. In Figures b and S6a, the absorption peaks at 3290, 1730, and 1085 cm –1 were respectively identified as belonging to the −OH, –CO, and C–O–C stretching vibrations, while the peaks at 1346 and 1431 cm –1 indicated the C–H rocking and bending. ,− A significant peak shift was observed from the spectra of the GO–aptamer–PVA, in which the peaks at 3290 and 1726 cm –1 moved to 3273 and 1709 cm –1 respectively, at lower wave numbers.…”

“…Then, XRD and TGA measurements of the hydrogels were performed. Compared to GO, the characteristic diffraction peak of GO–PVA (A-0) shifted from 10.36° to 7.16°, and the interlayer spacing increased from 8.53 to 12.33 Å (Figure c), indicating that there was a strong noncovalent interaction between PVA and the GO sheet. ,, When different concentrations of the aptamer were added, the characteristic peaks of A-1 and A-2 shifted to 6.72 and 6.68°, and the interlayer spacing increased to 13.15 and 13.22 Å, respectively. These results indicated the weak noncovalent interactions between aptamers and the GO sheet or PVA, , ensuring sufficient connection force between the aptamer and the hydrogel so that it would not fall off until it encountered specific antibiotics.…”