In order to improve the dispersibility in water, many researchers have

changed the surface modification of carbon spheres by using air oxidation and mixed acid oxidation. Zhang and colleagues [8] used phosphate group to increase the content of oxygen-containing functional groups on the surface of phosphorus-rich hydrothermal carbon spheres. Researchers [9] in Anhui Key Laboratory of Advanced Building Materials added ammonia to hydrothermal reaction solution to get carbon spheres with amino groups, which showed an excellent enhanced adsorption performance for the removal Wnt inhibitor of heavy metal anions. Liu et al. [10] introduced functional double bonds onto the surface of CSs by covalent and non-covalent method to improve CSs’ dispersibility and compatibility in polymer matrix, in which covalent functionalization was accomplished through mixed acid oxidation and subsequent reaction with acryloyl chloride. Lian et al. [11]

modified polystyrene-based activated carbon spheres with either air, HNO3, (NH4)2S2O8, H2O2, or H2 to improve their adsorption properties Selleckchem RAD001 of dibenzothiophene. Although many researches have been done to modify the surface of CSs, there was still potential damage to the structure of carbon materials [12]. In this paper, the method of grafting polyelectrolyte brushes on the surface of CSs was used to enhance the dispersibility of CSs in water. First, the CSs were prepared by hydrothermal reaction solution. Then, the process of grafting polyelectrolyte brushes was conducted on the surface of the CSs. The method of preparing CSs with hydrothermal reaction solution was environmental, simple, and can be easily controlled, and there were much more hydroxyl groups that could be obtained on the surface of CSs than any

other methods. Compared with air oxidation and mixed acid oxidation, the modification by grafting polyelectrolyte brushes on the surface of CSs would not influence the inner structure of CSs at all, and it could not only protect the original properties of CSs but also enable CSs to have some new and different properties because of the variability of kinds of polyelectrolyte brushes. In this paper, poly(diallyl dimethyl ammonium chloride) (p-DMDAAC) has been chosen ASK1 as the polyelectrolyte brush. After being grafted, CSs became more stable in water than before. Methods Raw materials and reagents The chemicals used in this study are the following: glucose (Guoyao Group of Chemical Reagents Ltd., Shanghai, China), 4,4′-Azobis (4-cyanovaleric acid) (ACVA; Aladdin Company, Shanghai, China), diallyl dimethyl ammonium chloride (DMDAAC; Aladdin Company, Shanghai, China), dichloromethane (Guoyao Group of Chemical Reagents Ltd.), hexane (Guoyao Group of Chemical Reagents Ltd.), ethanol, toluene, triethylamine, distilled water, and phosphorus pentachloride. All the chemicals and solvents used in this study were of analytical grade.