The aim of our work is to study structural properties of supra-molecular assemblies formed in aqueous solutions of cationic pH- and thermo-sensitive block-gradient copolymers comprising one block of poly(dimethylaminoethyl acrylate) (DMAEA) and one or two terminal blocks with a gradient sequence of styrene (S) and DMAEA monomer units. We expect that because of the gradient sequence of the terminal blocks such copolymers are capable of reversible association giving rise to micellar-like aggregates in aqueous solutions as a function of both pH and temperature. The cationic charge of the PDMAEA blocks opens the perspective to use this smart copolymer nanostructures as non-viral vectors for genetic material.