Sulfur-Dot-Mediated Synthesis of Smart Polymers for Heavy Metal Removal

An excellent level of control for the ambient temperature radical polymerization of 2-hydroxyethyl methacrylate (HEMA), yielding well-defined poly(2-hydroxyethyl)methacrylate (PHEMA) (at least up to 18900 g mol –1 ) with low dispersity (≤1.24), was achieved via ultrasmall S-dots-mediated reversible deactivation radical polymerization. The high chain-end functionality of synthesized PHEMA-Br was demonstrated by the synthesis of PHEMA and poly(2-hydroxyethyl methacrylate)- block -poly( tert -butyl methacrylate) (PHEMA- b -PtBMA) diblock copolymers. Hydrolysis of the tert -butyl ester groups of the PtBMA segment led to the synthesis of dual thermo/pH-responsive poly(2-hydroxyethyl methacrylate)- block -poly(methacrylic acid) (PHEMA- b -PMAA) diblock copolymer, bearing thermoresponsive PHEMA and pH-responsive PMAA segments. This polymer is responsible for lead (Pb) removal from wastewater.