Spectral grade THF was used as an eluent at a flow rate of 1.0 ml min−1, and the molecular weight calibrations were carried out using polystyrene standards. Results
and discussion In general, good interaction between fillers and polymers leads to significant improvements in the properties of the resulting final products. To increase the interfacial interactions between GO and the polymers, the GO was first diazotized with p-aminobenzoic acid to obtain DGO-COOH, followed by a quaternization reaction with THAC and an esterification reaction with α-bromoisobutyryl bromide, which resulted selleck kinase inhibitor in a tertiary bromine-terminated PI3K inhibitor DGO-Br for efficient ATRP, as shown in Figure 1. Detailed characterizations of GO, DGO-COOH, and DGO-OH through FT-IR, Raman, XPS, XRD, and TGA have been reported in our Luminespib manufacturer previous paper [21]. In addition, XPS was used to investigate the changes in the functional
groups of DGO-OH and DGO-Br, as shown in Figure 2a. Two intense peaks at 285 and 532 eV can be attributed to C1s and O1s, respectively [22]. The new peak of N1s at 399 to 400 eV was observed by diazotization. The C/O ratios of the functionalized DGO-OH and DGO-Br were 2.5 and 2.65, respectively, which can be correlated with dehydration during the esterification of DGO-OH to DGO-Br. The deconvoluted C1s XPS spectra of DGO-Br (Figure 2b) show several peaks at 284.5, 286.3, 287.9, and 289.7 eV originating from C-C, C-O, C = O, and O-C = O groups, respectively. In comparison to DGO-OH [21], the relative intensity of the C-C peak remains RAS p21 protein activator 1 the same after esterification, but the intensity of the C = O and O-C = O peaks increased, which may be due to increased functionality. Figure 1 Schematic representation of the synthetic procedures of the graphene-polymer nanocomposites. Figure 2 XPS survey data, C1s core level data, Raman spectra, and XRD pattern. XPS survey data of (a) (i) DGO-OH, (ii) DGO-Br; C1s core level data of (b) DGO-Br; Raman spectra of (c) (i) DGO-OH, (ii) DGO-Br; and XRD pattern of (d) (i)
DGO-OH, (ii) DGO-Br. Raman spectra of DGO-OH and DGO-Br are shown in Figure 2c. The G and D bands in the Raman spectra originate from the first-order scattering of E2g phonons of sp2-bonded carbon atoms and with a breathing mode of j-point photons of A1g symmetry of sp3-bonded carbon atoms of disordered graphene. The Raman spectrum of DGO-OH shows sp2-bonded carbon stretching related to the G band at 1,594 cm−1 and disordered, D band, sp3-bonded carbon atoms at 1,330 cm−1. The intensity ratio of the D and G bands (I D/I G) for DGO-OH and DGO-Br were 1.3 and 1.35, respectively. The slightly increased I D/I G ratio may be due to increased functionalization after esterification. WAXRD patterns of DGO-OH and DGO-Br are shown in Figure 2d.