PEO-based block copolymers and homopolymers as reactive surfactants for AGET ATRP of butyl acrylate in miniemulsion

Amphiphilic block copolymers poly(ethylene oxide)-b-polystyrene (PEO-PS-Br) with various molecular weights and poly(ethylene oxide) homopolymer (PEO-Br) were synthesized and used as macroinitiators and stabilizers (reactive surfactants) for activator generated by electron transfer atom transfer radical polymerization (AGET ATRP) of n-butyl acrylate (BA), in miniemulsion either with or without ethyl 2-bromoisobutyrate (EBiB) as co-initiator. Under both conditions, the reactions were well controlled and stable latexes were formed. In the absence of EBiB, polymer particles with diameter around 120-230 not were obtained, and the particles contained polymers with molecular weight M-n = 16 000-25 000 g/mol and relatively low polydispersity (M-w/M-n = 1.2-1.4). In the presence of a low molecular weight initiator, EBiB, the amount of surfactant used can be reduced in the reaction (1.7-4 wt % vs monomer). The percent of initiating sites from EBiB was changed from 30% to 90%, and the majority of the obtained polymers were initiated by EBiB. Nevertheless, because of the covalent linking of the surfactants to polymer chains, no free surfactant was left in the reaction system. The final diameter of latexes stabilized by reactive surfactants was around 200-390 nm, the number-average molecular weight Mn of the polymers obtained was 10 000-25 000 g/mol, and the polydispersity index was around 1.2.