The synthesis and properties of double hydrophilic block copolymers (DHBCs) are explored in the present work. These copolymers, denoted PSSNa-b-PNIPAM or PSSNa-b-PDMAM, are composed by an anionic poly(sodium styrenesulfonate), PSSNa, block and a thermosensitive poly(N-isopropylacrylamide), PNIPAM, or a hydrophilic poly(N,N-dimethylacrylamide), PDMAM, block, respectively. Core-shell nanoparticles, with a solidlike hydrophobic PNIPAM core and a hydrophilic PSSNa shell, are stabilized in water upon heating the aqueous PSSNa-b-PNIPAM solutions above the lower critical solution temperature of PNIPAM. The association of the diblock copolymers with the cationic surfactant cetyltrimethylammonium bromide, CTAB, was investigated as a function of charge mixing ratio and temperature, through turbidimetry, dynamic light scattering, zeta-potential measurements, and H-1 NMR spectroscopy. It is shown that both blocks of the PSSNa-b-PNIPAM DHBCs are able to associate with CTAB. The association process is sequential; namely, the mixed PNIPAM/CTAB aggregates are formed only when the PSSNa/CTAB complexation has been completed.