Synthesis of highly surface functionalized monodispersed poly(St/DVB/GMA) nanospheres with soap-free emulsion polymerization followed by facile “click chemistry” with functionalized alkylthiols

Poly(St/DVB/GMA) nanospheres (PNs) were prepared by soap-free emulsion polymerization and the surfaces of the PNs were further functionalized by the thiol-epoxy “click-chemistry” of surface pendant epoxy groups with functional thiols. A variety of functional groups were successfully grafted to the PNs surfaces at high densities as exemplified by the reactions with 2-aminoethanethiol, thioglycolic acid, and 2-mercaptoethanol. All the reactions were easily controlled and the modified polymer nanospheres were well-dispersed in water. Very high surface charges were observed for the 2-aminoethanethiol and thioglycolic acid modified PNs in water, a manifestation of the high surface grafting densities of the ionizable groups. The adsorptions of acid orange and toluidine blue to, respectively, the 2-aminoethanethiol and thioglycolic acid functionalized PNs were examined, which fitted well to the Langmuir isotherm model. For the 2-aminoethanethiol modified PNs, the surface amino group density was found to be 1.1 mequiv/g, with an adsorption capacity of 398 mg/g of acid orange; while the thioglycolic acid modified PNs displayed 1.4 mequiv/g carboxylate groups and an adsorption capacity of 416 mg/g for toluidine blue. The new synthetic method appears to be general in scope and adaptive to a variety of surface functionalities and potential applications.