Unravelling the formation of BAB block copolymer assemblies during PISA in water

Abstract

The mechanism of formation of associative BAB triblock copolymers through aqueous polymerization-induced self-assembly (PISA) is investigated for the first time, on copolymers constituted of a hydrophilic poly(N,N-dimethylacrylamide) block (PDMAc = block A) and a hydrophobic poly(diacetone acrylamide) block (PDAAm = block B). Such BAB copolymers tend to form bridged micelles/networks, which was expected to make the PISA process much more complex than for conventional diblock copolymers. Kinetic monitoring, light scattering analyses and macroscopic observations allowed identifying crucial parameters that influence the polymerization and the final dispersion properties, notably the stirring of the polymerization medium, the macroRAFT agent concentration, its ionization degree (related to the pH) and its Z group alkyl chain length.