The weight of p-DMDAAC-CSs (m) could be calculated according to formula (1). The percentage of the grafted p-DMDAAC-CSs and surface grafting density (σ) were calculated according to formula (2). (1) where m 0 is the weight of the CSPBs used for TGA, w 0% is the weight

loss of the CSPBs during the temperature rise from 190°C to 475°C, w 1% is the mass loss of the pure CSs in the same temperature, and w% stood for the mass loss of p-DMDAAC-WL. (2) where Mw is the weight-average molecular weight of p-DMDAAC-CSs, and r is the average size of the CSs. Conductivity tests Conductivity has been tested to compare the promotion of conductive performance of CSs and CSPBs. A 1.5-mg/ml solution of CSs and PLX4032 supplier CSPBs was prepared with water as solvent. The conductivity of CSs and CSPBs water solution was 9.98 and 49.24 μS/cm, respectively.

It can be turned out that the conductivity of CSs increased with the grafting of p-DMDAAC on the surface of the CSs. As shown in Figure 5, the conductive performance of CSPBs decreased with the increase of ionic strength by adding the amount of salt. The reason for this phenomenon was that with the increasing ionic strength, the Debye length diminished [16], inducing the decreasing of the points on the polyelectrolyte brushes. Figure 5 Conductivity of CSPBs in different concentrations of NaCl. Zeta potential and colloidal stability analysis Metabolism inhibitor The zeta potential on the CSs and CSPBs was 11.6 and 42.5 mV, respectively. It showed that polyelectrolyte was successfully grafted on the CSs. And the increase gained in the aspect of zeta potential enabled CSPBs to have better stability in water. As shown in Figure 6, the stratification of CSs appeared 30 s after ultrasonic dispersion, while the CSPBs appeared 1 h later. Figure 6 Dispersibility of (a) CSs and

(b) CSPBs at different times in water. Conclusion Parvulin Surface modification of carbon spheres by grafting p-DMDAAC on their surfaces has been described, and a series of characterization was done. Using FTIR, SEM, conductivity meter, and zeta potential method, the chemical structure, morphology, conductivity, and water dispersibility of the modified CSs were represented. Owing to the p-DMDAAC-CSs, the dispersibility of CSPBs in water has been enhanced obviously, which will expand its application in liquor phase. Because the weight-average molecular weight and surface grafting density can be controlled by adjusting monomer concentration and reaction time, CSPBs with different performances will be obtained; thus, this will further expand its application field. Authors’ information HL is a professor in the School of Printing and Packing at Wuhan University, China. He is a Ph.D. supervisor. His main research interests include packing materials, packing auxiliary materials, and printing materials. QZ, PZ, and YW are studying for a masters degree at Wuhan University.