Aqueous solution properties of amphiphilic P(AA-co-tBA)-b-PPO-b- P(AA-co-tBA) copolymers having various tBA contents are presented in this article. These copolymers show pH-sensitive behavior depending on tBA/AA ratio. Hydrophobic interactions between tBA units leading to pH-dependent macroscopic aggregates were evidenced by turbidimetry. The aggregation behavior of the PPO middle block was concealed in presence of tBA units. The formation of water-soluble aggregated objects was characterized by Asymmetrical Flow Field Flow Fractionation (AsF4). By increasing tBA/AA ratio, we observed an increase of aggregates size as well as a reduction of the critical concentration aggregation. (c) 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 1944-1949