Ltd., Guangdong, China). Zeta potential on CSs and CSPBs was tested by system zeta potential (Zetasizer Nano-ZS, Malvern Instruments Ltd., Malvern, UK). Results and discussion Morphology analysis The morphologies of CSs, CSPBs, and p-DMDAAC-WL are displayed in Figure 2a,b,c, respectively. The average diameter of CSPBs was 173 nm, larger than that of CSs (153 nm). It indicated that there were indeed some polymer brushes on the CSs’ surface. As shown in Figure 1, there existed three kinds of patterns for this polymerization. If the reaction occurred as route b or c, there would be no polymer appearing in the washing liquor of the CSPBs. However, from Figure 2c, bulk polymer (p-DMDAAC-WL)
has been seen obviously. Thus, it can be confirmed that this website in the synthesis of immobilizing ACVC on CSs, the main products obtained were in the single-ended form grafted on CSs (see Figure 1a). Owing to the breaking of the azo linkage, half of the initiator was
detached from the surface of the CSs, which induced homopolymerization of DMDAAC. Figure 2 SEM photographs. (a) CSs, (b) CSPBs, and (c) p-DMDAAC-WL. FTIR analysis The successful synthesis of 4,4′-Azobis (4-cyanovaleric acyl chloride) was testified by FTIR (see Figure 3 spectrum ATM/ATR signaling pathway a). The vibration absorption peaks of -COCl (at 1,790 cm-1) and -C ≡ N (at 2,246 cm-1) were observed obviously. The FTIR spectrum of CSs (see Figure 3 spectrum c) buy BIIB057 showed strong vibration absorption peaks of -OH (at 3,427 cm-1). A new peak in the FTIR spectrum of CSs immobilizing with ACVC (see Figure 3 spectrum b) indicated that CSs induced redshift of the vibration absorption of -COCl, jumping from 1,790 to 1,827 cm-1. The peak at 1,111 cm-1 represented -C-O-C- for CSs immobilizing with ACVC. Figure 3 FTIR spectra. (a) ACVC, (b) ACVC immobilized on CSs, and (c) CSs. Thermal stability Because it is difficult to calculate the weight of p-DMDAAC-CSs, thermogravimetry analysis of CSs, CSPBs, and p-DMDAAC-WL has been done, respectively, to distinguish the proportion of CSs and p-DMDAAC in CSPBs. As shown in Figure 4, the mass loss below 190°C shown in all these
three curves implied a loss of moisture. From the curve of p-DMDAAC-CSs (see Figure 4 curve c), it could be ensured that the washing liquor of CSPBs was p-DMDAAC . As shown in Figure 4 curve b, the mass loss (10%) from 190°C to 330°C Thymidine kinase was mainly the decomposition of p-DMDAAC-CSs. And the stage from 330°C to 430°C mainly implied the loss of CSs (12%). During the period from 430°C to 475°C, mass loss contains both CSs and p-DMDAAC-CSs (7%). Figure 4 Thermography curves. (a) Pure CSs, (b) CSPBs, and (c) p-DMDAAC-WL. Calculation of surface grafting density As shown in Figure 4 curve b, the weight loss (28%) from 190°C to 475°C contained the decomposition of both CSs and p-DMDAAC-CSs. The weight loss of CSs and p-DMDAAC-CSs during the same period was 19.5% and 86%, respectively (as shown in Figure 4 curves a and c).