Polymerization of sodium 4-styrenesulfonate via atom transfer radical polymerization in protic media

The homopolymerization of sodium 4-styrenesulfonate (NaStS) in both aqueous and water/methanol solutions at 20 °C using atom transfer radical polymerization (ATRP) is described. Syntheses conducted using a sodium 4-bromomethylbenzoate initiator were poorly controlled in water but reasonably well-controlled in 1:1 water/methanol mixtures, with 3:1 water/methanol mixtures exhibiting intermediate behavior. In 1:1 water/methanol mixtures aqueous GPC analyses indicated polydispersities as low as 1.26 and conversions reached 80–90% within 18–20 h at 20 °C. Self-blocking experiments were conducted in 1:1 water/methanol mixtures, with the chain-extended NaStS polymers exhibiting unimodal GPC traces but relatively high polydispersities (Mw/Mn=1.61). The use of poly(ethylene oxide)-based (PEO) macro-initiators yielded novel PEO–NaStS diblock copolymers of low polydispersity. Diblock copolymer syntheses via sequential monomer addition were less satisfactory, although one example of a polydisperse pH-responsive diblock copolymer was obtained.