Triblock copolymers of BAB type were synthesized by ATRP with a poly(acrylic acid) central block and random copolymer end blocks containing both acrylic acid (AA) and hydrophobic n-butyl acrylate (nBA) units with varied composition of the B-blocks. Visco-elastic properties of these amphiphilic polymers were investigated by oscillatory shear measurements as a function of composition, concentration, temperature and pH. Whatever the composition for each polymer the terminal relaxation time and thus the viscosity increased sharply with decreasing degree of ionization of the AA units (alpha) and at low values self-supporting hydrogels were formed. However, the alpha- (respectively pH-) dependence of the terminal relaxation time as well as the critical range of alpha (respectively pH) where a transition between visco-elastic solutions and self-supporting hydrogels occurs strongly depend on the composition of the B-block.