Quasi-block copolymer design of quaternized derivatives of poly(2-(dimethylamino)ethyl methacrylate): Investigations on thermo-induced self-assembly

We describe the sequential incorporation of the quaternized monomer N-(2-(Methacryloyloxy)ethyl)-N,N-dimethylheptan-l-ammonium (QDM) (from 1 up to 5 mol %) into 2-((dimethylamino)ethyl methacrylate) polymer chains (PDMAEMA), via reversible addition-fragmentation chain transfer (RAFT) technique, to yield quasi-block copolymers (PDMAEMA-qb-P(DMAEMA-co-QDM)) with modified hydrophilic nature and thermo-induced self-assembly properties in aqueous solutions. This chemical modification promotes the formation of metastable nanostructures in aqueous medium. The morphological transitions were investigated by means of atomic force microscopy (AFM), dynamic light scattering (DLS), rheology and turbidimetry. The results indicated that the obtained nanostructures were stabilized by associative and cationic interactions conveyed by the quaternized moieties within the polymer chains. The size of these nanostructures could be modified as a function of molar mass, copolymer composition and temperature. The method described denotes an interesting alternative to modify the thermo-induced self-assembly behavior of PDMAEMA based copolymers employing low amounts of quaternized moieties.